Species List
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| Scientific Name | Common Name | Family | New England Distribution | N. American Native | Wetland Code | Group | Subgroup | 
|---|---|---|---|---|---|---|---|
| Abelmoschus esculentus | okra | Malvaceae | CT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Abies balsamea | balsam fir | Pinaceae | CT MA ME NH RI VT | Yes and no (some introduced) | Woody Plants | Needle-leaved woody plants | |
| Abies concolor | white fir | Pinaceae | MA ME VT | Yes | Woody Plants | Needle-leaved woody plants | |
| Abies homolepis | Nikko fir | Pinaceae | RI | No | Woody Plants | Needle-leaved woody plants | |
| Abutilon pictum | painted Indian-mallow | Malvaceae | CT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Abutilon theophrasti | velvetleaf Indian-mallow | Malvaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Acalypha gracilens | slender three-seeded-Mercury | Euphorbiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Acalypha rhomboidea | common three-seeded-Mercury | Euphorbiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Acalypha virginica | Virginia three-seeded-Mercury | Euphorbiaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Acanthospermum australe | Paraguay starburr | Asteraceae | MA | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Acer campestre | hedge maple | Sapindaceae | MA VT | No | Woody Plants | Broad-leaved woody plants | |
| Acer ginnala | Amur maple | Sapindaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Acer negundo | ash-leaved maple, boxelder | Sapindaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Acer nigrum | black maple | Sapindaceae | CT MA NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Acer palmatum | Japanese maple | Sapindaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Acer pensylvanicum | goosefoot maple, striped maple | Sapindaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Acer platanoides | Norway maple | Sapindaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Acer pseudoplatanus | sycamore maple | Sapindaceae | CT MA ME RI | No | Woody Plants | Broad-leaved woody plants | |
| Acer rubrum | red maple | Sapindaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Acer saccharinum | silver maple | Sapindaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Acer saccharum | sugar maple | Sapindaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Acer spicatum | mountain maple | Sapindaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Acer tataricum | Tatarian maple | Sapindaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Achillea filipendulina | fern-leaved yarrow | Asteraceae | VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Achillea ligustica | Ligurian yarrow | Asteraceae | VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Achillea millefolium | common yarrow | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Achillea ptarmica | pearl yarrow | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Achillea tomentosa | woolly yarrow | Asteraceae | MA | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Aconitum napellus | garden monkshood | Ranunculaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Aconitum uncinatum | wild monkshood | Ranunculaceae | NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Acorus americanus | several-veined sweetflag | Acoraceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Acorus calamus | single-veined sweetflag | Acoraceae | CT MA ME NH RI VT | No | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Actaea pachypoda | doll's-eyes, white baneberry | Ranunculaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Actaea racemosa | black bugbane | Ranunculaceae | CT MA ME NH | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Actaea rubra | red baneberry | Ranunculaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Actinidia arguta | taravine | Actinidiaceae | CT MA ME | No | Woody Plants | Broad-leaved woody plants | |
| Adiantum aleuticum | western maidenhair fern | Pteridaceae | ME VT | Yes | Ferns | True ferns and moonworts | |
| Adiantum pedatum | northern maidenhair fern | Pteridaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Adiantum viridimontanum | Green Mountain maidenhair fern | Pteridaceae | ME VT | Yes | Ferns | True ferns and moonworts | |
| Adlumia fungosa | Allegheny-vine | Papaveraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Aegilops cylindrica | jointed goat-grass | Poaceae | MA | No | Grass-like plants | True grasses | |
| Aegopodium podagraria | bishop's goutweed | Apiaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Aesculus glabra | Ohio buckeye | Sapindaceae | NH | Yes | Woody Plants | Broad-leaved woody plants | |
| Aesculus hippocastanum | horse-chestnut | Sapindaceae | CT MA ME RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Aethusa cynapium | fool's-parsley | Apiaceae | CT MA ME RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Agalinis acuta | sandplain agalinis | Orobanchaceae | CT MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Agalinis maritima | saltmarsh agalinis, saltmarsh false-foxglove | Orobanchaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Agalinis neoscotica | Nova Scotia agalinis | Orobanchaceae | ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Agalinis paupercula | small-flowered agalinis, small-flowered false-foxglove | Orobanchaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Agalinis purpurea | purple agalinis, purple false-foxglove | Orobanchaceae | CT MA ME RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Agalinis tenuifolia | slender-leaved agalinis, slender-leaved false-foxglove | Orobanchaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Agastache foeniculum | lavender giant-hyssop | Lamiaceae | CT NH RI | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Agastache nepetoides | catnip giant-hyssop | Lamiaceae | CT VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Agastache scrophulariifolia | purple giant-hyssop | Lamiaceae | CT MA NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Ageratina altissima | white snakeroot | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Ageratina aromatica | lesser snakeroot | Asteraceae | CT MA RI | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Ageratum conyzoides | tropical whiteweed | Asteraceae | CT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Ageratum houstonianum | Houston's whiteweed | Asteraceae | MA | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Agrimonia eupatoria | medicinal agrimony | Rosaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Agrimonia gryposepala | common agrimony, tall hairy agrimony | Rosaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Agrimonia microcarpa | low agrimony | Rosaceae | CT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Agrimonia parviflora | southern agrimony | Rosaceae | CT MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Agrimonia pubescens | downy agrimony | Rosaceae | CT MA RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Agrimonia rostellata | woodland agrimony | Rosaceae | CT MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Agrimonia striata | roadside agrimony | Rosaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Agropyron cristatum | crested wheat grass | Poaceae | MA NH | No | Grass-like plants | True grasses | |
| Agropyron desertorum | clustered wheat grass | Poaceae | MA | No | Grass-like plants | True grasses | |
| Agrostemma githago | common corncockle | Caryophyllaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Agrostis canina | dog bentgrass | Poaceae | CT MA ME NH RI | No | Grass-like plants | True grasses | |
| Agrostis capillaris | colonial bentgrass, Rhode Island bentgrass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Agrostis elliottiana | Elliott's bentgrass | Poaceae | MA ME | Yes | Grass-like plants | True grasses | |
| Agrostis exarata | spike bentgrass | Poaceae | VT | Yes | Grass-like plants | True grasses | |
| Agrostis gigantea | redtop bentgrass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Agrostis hyemalis | winter bentgrass | Poaceae | CT MA ME NH RI | Yes | Grass-like plants | True grasses | |
| Agrostis mertensii | northern bentgrass | Poaceae | ME NH VT | Yes | Grass-like plants | True grasses | |
| Agrostis perennans | autumn bentgrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Agrostis scabra | rough bentgrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Agrostis stolonifera | creeping bentgrass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Ailanthus altissima | tree-of-heaven | Simaroubaceae | CT MA RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Aira caryophyllea | common silver-hairgrass | Poaceae | CT MA NH VT | No | Grass-like plants | True grasses | |
| Aira praecox | early silver-hairgrass | Poaceae | CT MA | No | Grass-like plants | True grasses | |
| Aizopsis aizoon | aizoon stonecrop | Crassulaceae | MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Aizopsis kamtschatica | orange stonecrop | Crassulaceae | ME NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ajuga genevensis | standing bugle | Lamiaceae | CT MA ME RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Ajuga reptans | carpet bugle | Lamiaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Akebia quinata | chocolate-vine | Lardizabalaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Albizia julibrissin | silk-tree | Fabaceae | CT | No | Woody Plants | Broad-leaved woody plants | |
| Alcea rosea | hollyhock | Malvaceae | CT MA NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Alchemilla monticola | hairy lady's-mantle | Rosaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Aletris farinosa | white colic-root | Nartheciaceae | CT MA ME NH RI | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Alisma gramineum | narrow-leaved water-plantain | Alismataceae | VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Alisma subcordatum | southern water-plantain | Alismataceae | CT MA ME NH RI VT | Yes | Orchids and related plants; Aquatic plants | Irises, lilies, and other "monocots"; Water plants with leaves and stems | |
| Alisma triviale | northern water-plantain | Alismataceae | CT MA ME NH RI VT | Yes | Aquatic plants; Orchids and related plants | Water plants with leaves and stems; Irises, lilies, and other "monocots" | |
| Alliaria petiolata | garlic-mustard | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Allium canadense | meadow garlic | Alliaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Allium cepa | garden onion | Alliaceae | CT MA ME NH VT | No | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Allium oleraceum | field garlic | Alliaceae | MA | No | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Allium sativum | cultivated garlic | Alliaceae | MA VT | No | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Allium schoenoprasum | wild chives | Alliaceae | CT MA ME NH RI VT | Yes and no (some introduced) | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Allium tricoccum | ramps, wild leek | Alliaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Allium vineale | crow garlic | Alliaceae | CT MA ME NH RI VT | No | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Alnus glutinosa | European alder | Betulaceae | CT MA ME RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Alnus incana | speckled alder | Betulaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Alnus serrulata | smooth alder | Betulaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Alnus viridis | green alder | Betulaceae | MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Alopecurus aequalis | short-awned meadow-foxtail | Poaceae | CT MA ME NH VT | Yes | Grass-like plants | True grasses | |
| Alopecurus carolinianus | Carolina meadow-foxtail | Poaceae | MA | Yes | Grass-like plants | True grasses | |
| Alopecurus geniculatus | marsh meadow-foxtail | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Alopecurus myosuroides | slender meadow-foxtail | Poaceae | MA ME | No | Grass-like plants | True grasses | |
| Alopecurus pratensis | field meadow-foxtail | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Alternanthera pungens | khaki joyweed | Amaranthaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Althaea officinalis | common marsh-mallow | Malvaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Alyssum alyssoides | pale alyssum | Brassicaceae | CT MA ME RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amaranthus albus | tumbleweed amaranth | Amaranthaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amaranthus blitoides | prostrate amaranth | Amaranthaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amaranthus blitum | livid amaranth | Amaranthaceae | CT MA RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amaranthus cannabinus | saltmarsh water-hemp | Amaranthaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amaranthus caudatus | purple amaranth | Amaranthaceae | CT MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amaranthus cruentus | blood amaranth | Amaranthaceae | CT MA NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amaranthus deflexus | large-fruited amaranth | Amaranthaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amaranthus dubius | spleen amaranth | Amaranthaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amaranthus hybridus | green amaranth | Amaranthaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amaranthus hypochondriacus | prince's-feather amaranth | Amaranthaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amaranthus macrocarpus | dwarf amaranth | Amaranthaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amaranthus palmeri | Palmer's amaranth | Amaranthaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amaranthus powellii | Powell's amaranth | Amaranthaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amaranthus pumilus | sea-side amaranth | Amaranthaceae | CT MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amaranthus retroflexus | red-rooted amaranth | Amaranthaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amaranthus spinosus | spiny amaranth | Amaranthaceae | CT MA RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amaranthus tuberculatus | rough-fruited water-hemp | Amaranthaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amaranthus viridis | slender amaranth | Amaranthaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amberboa moschata | sweet sultan | Asteraceae | ME | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Ambrosia artemisiifolia | common ragweed | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Ambrosia bidentata | lance-leaved ragweed | Asteraceae | CT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Ambrosia psilostachya | perennial ragweed | Asteraceae | CT MA ME NH VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Ambrosia trifida | giant ragweed | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Amelanchier arborea | common serviceberry, downy shadbush | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Amelanchier bartramiana | Bartram's serviceberry, mountain shadbush | Rosaceae | MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Amelanchier canadensis | Canadian serviceberry, eastern shadbush | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Amelanchier gaspensis | Gaspe serviceberry, Gaspe shadbush | Rosaceae | ME | Yes | Woody Plants | Broad-leaved woody plants | |
| Amelanchier humilis | low serviceberry, low shadbush | Rosaceae | VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Amelanchier intermedia | intermediate serviceberry, intermediate shadbush | Rosaceae | ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Amelanchier laevis | smooth serviceberry, smooth shadbush | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Amelanchier nantucketensis | Nantucket serviceberry, Nantucket shadbush | Rosaceae | CT MA ME NH RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Amelanchier sanguinea | round-leaved serviceberry, round-leaved shadbush | Rosaceae | MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Amelanchier spicata | dwarf serviceberry, dwarf shadbush | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Amerorchis rotundifolia | round-leaved orchid | Orchidaceae | ME NH VT | Yes | Orchids and related plants | Orchids | |
| Ammophila breviligulata | American beach grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Amorpha fruticosa | false indigo-bush | Fabaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Ampelopsis cordata | heart-leaved peppervine | Vitaceae | CT | Yes | Woody Plants | Broad-leaved woody plants | |
| Ampelopsis glandulosa | Amur peppervine | Vitaceae | CT MA NH RI | No | Woody Plants | Broad-leaved woody plants | |
| Amphicarpaea bracteata | American hog-peanut | Fabaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amphicarpum amphicarpon | Pursh's blue maidencane | Poaceae | MA | Yes | Grass-like plants | True grasses | |
| Amsinckia eastwoodiae | Eastwood's fiddleneck | Boraginaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amsinckia lycopsoides | bugloss fiddleneck | Boraginaceae | CT MA NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amsinckia menziesii | rancher's fiddleneck | Boraginaceae | CT MA ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Amsonia tabernaemontana | eastern bluestar | Apocynaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Anaphalis margaritacea | pearly everlasting | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Anchusa arvensis | small bugloss | Boraginaceae | CT MA ME NH RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Anchusa azurea | Italian bugloss | Boraginaceae | CT MA NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Anchusa officinalis | common bugloss | Boraginaceae | CT MA ME NH RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Andromeda polifolia | bog-rosemary | Ericaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Andropogon gerardii | big bluestem | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Andropogon glomeratus | bushy bluestem | Poaceae | MA RI | Yes | Grass-like plants | True grasses | |
| Andropogon virginicus | broomsedge bluestem | Poaceae | CT MA RI | Yes | Grass-like plants | True grasses | |
| Androsace occidentalis | western androsace | Primulaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Anemone acutiloba | sharp-lobed hepatica | Ranunculaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Anemone americana | blunt-lobed hepatica | Ranunculaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Anemone blanda | Greek windflower | Ranunculaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Anemone canadensis | Canada windflower, Canadian anemone | Ranunculaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Anemone cylindrica | long-headed windflower | Ranunculaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Anemone multifida | cut-leaved windflower | Ranunculaceae | ME VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Anemone nemorosa | European windflower | Ranunculaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Anemone quinquefolia | wood anemone, wood windflower | Ranunculaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Anemone virginiana | tall anemone, tall windflower | Ranunculaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Anethum graveolens | dill | Apiaceae | CT MA ME RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Angelica atropurpurea | purple-stemmed Angelica | Apiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Angelica lucida | sea coast Angelica | Apiaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Angelica venenosa | hairy Angelica | Apiaceae | CT MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Anoda cristata | crested anoda | Malvaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Antennaria howellii | small pussytoes | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Antennaria neglecta | field pussytoes | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Antennaria parlinii | Parlin's pussytoes | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Antennaria plantaginifolia | plantain-leaved pussytoes | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Anthemis arvensis | corn chamomile | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Anthemis cotula | stinking chamomile | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Anthoxanthum hirtum | northern sweet grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Anthoxanthum monticola | alpine sweet grass | Poaceae | ME NH VT | Yes | Grass-like plants | True grasses | |
| Anthoxanthum nitens | sweetgrass, vanilla sweet grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Anthoxanthum odoratum | large sweet grass, sweet vernalgrass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Anthoxanthum ovatum | small sweet grass | Poaceae | MA ME NH | No | Grass-like plants | True grasses | |
| Anthriscus cerefolium | garden chervil | Apiaceae | CT VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Anthriscus sylvestris | wild chervil | Apiaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Anthyllis vulneraria | common kidney-vetch | Fabaceae | CT NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Anticlea elegans | mountain death camas | Melanthiaceae | VT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Antirrhinum majus | garden snapdragon | Plantaginaceae | CT MA VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Apera interrupta | dense silky bentgrass | Poaceae | MA ME | No | Grass-like plants | True grasses | |
| Apera spica-venti | loose silky bentgrass | Poaceae | CT MA ME VT | No | Grass-like plants | True grasses | |
| Apios americana | common ground-nut | Fabaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Apium graveolens | celery | Apiaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Aplectrum hyemale | putty-root | Orchidaceae | CT MA VT | Orchids and related plants | Orchids | ||
| Apocynum androsaemifolium | spreading dogbane | Apocynaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Apocynum cannabinum | hemp dogbane | Apocynaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Aquilegia canadensis | red columbine | Ranunculaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Aquilegia vulgaris | European columbine | Ranunculaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Arabidopsis lyrata | lyre-leaved thale-cress | Brassicaceae | CT MA VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Arabidopsis thaliana | mouse-ear thale-cress | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Arabis procurrens | running eared-rockcress | Brassicaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Arabis pycnocarpa | hairy eared-rockcress | Brassicaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Arachis hypogaea | peanut | Fabaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Aralia elata | Japanese angelica-tree | Apiaceae | CT MA NH | No | Woody Plants | Broad-leaved woody plants | |
| Aralia hispida | bristly sarsaparilla | Apiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Aralia nudicaulis | wild sarsaparilla | Apiaceae | CT MA ME NH RI VT | Yes | Woody Plants; All other flowering non-woody plants | Broad-leaved woody plants; Other herbaceous, flowering plants with alternate leaves | |
| Aralia racemosa | American spikenard | Apiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Aralia spinosa | Hercules'-club | Apiaceae | CT MA RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Arceuthobium pusillum | dwarf mistletoe | Viscaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Arctanthemum arcticum | arctic-daisy | Asteraceae | MA | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Arctium lappa | great burdock | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Arctium minus | common burdock | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Arctium tomentosum | woolly burdock | Asteraceae | CT MA ME NH VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Arctostaphylos uva-ursi | kinnikinnick, red bearberry | Ericaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Arctotis stoechadifolia | African-daisy | Asteraceae | MA | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Arctous alpina | alpine-bearberry | Ericaceae | ME NH | Yes | Woody Plants | Broad-leaved woody plants | |
| Arenaria serpyllifolia | thyme-leaved sandwort | Caryophyllaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Arethusa bulbosa | dragon's-mouth | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Argemone albiflora | white prickly-poppy | Papaveraceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Argemone mexicana | Mexican prickly-poppy | Papaveraceae | CT MA VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Argentina anserina | common silverweed | Rosaceae | MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Argentina egedii | Pacific silverweed | Rosaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Arisaema dracontium | green-dragon | Araceae | CT MA NH VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Arisaema triphyllum | Jack-in-the-pulpit | Araceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Aristida basiramea | fork-tipped threeawn | Poaceae | MA ME NH VT | Yes | Grass-like plants | True grasses | |
| Aristida dichotoma | churchmouse threeawn | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Aristida longespica | red threeawn | Poaceae | CT MA NH RI VT | Yes | Grass-like plants | True grasses | |
| Aristida oligantha | oldfield threeawn | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Aristida purpurascens | arrow-feather threeawn | Poaceae | CT MA RI | Yes | Grass-like plants | True grasses | |
| Aristida purpurea | purple threeawn | Poaceae | VT | Yes | Grass-like plants | True grasses | |
| Aristida tuberculosa | seaside threeawn | Poaceae | CT MA NH | Yes | Grass-like plants | True grasses | |
| Aristolochia clematitis | creeping birthwort | Aristolochiaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Armoracia rusticana | horse-radish | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Arnica lanceolata | lance-leaved arnica | Asteraceae | ME NH VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Arnoseris minima | lamb-succory | Asteraceae | ME NH | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Aronia arbutifolia | red chokeberry | Rosaceae | CT MA ME NH RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Aronia floribunda | purple chokeberry | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Aronia melanocarpa | black chokeberry | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Arrhenatherum elatius | tall oat grass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Artemisia abrotanum | southern wormwood | Asteraceae | CT MA ME VT | No | All other flowering non-woody plants; Woody Plants | Daisies, goldenrods, and other Aster family plants; Broad-leaved woody plants | |
| Artemisia absinthium | oldman wormwood | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Artemisia annua | annual wormwood, sweet sagewort | Asteraceae | CT MA ME NH VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Artemisia biennis | biennial wormwood | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Artemisia campestris | field wormwood | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Artemisia carruthii | Carruth's wormwood | Asteraceae | RI | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Artemisia dracunculus | dragon wormwood | Asteraceae | CT MA | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Artemisia frigida | prairie wormwood | Asteraceae | CT MA | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Artemisia ludoviciana | white wormwood | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Artemisia pontica | Roman wormwood | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Artemisia stelleriana | beach wormwood | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Artemisia tridentata | big sagebrush | Asteraceae | MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Artemisia vulgaris | common wormwood | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Arthraxon hispidus | small carp grass | Poaceae | CT MA | No | Grass-like plants | True grasses | |
| Aruncus dioicus | goat's beard | Rosaceae | MA ME | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Asarum canadense | Canada wild ginger | Aristolochiaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Asclepias amplexicaulis | clasping milkweed | Apocynaceae | CT MA NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Asclepias exaltata | poke milkweed | Apocynaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Asclepias incarnata | swamp milkweed | Apocynaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Asclepias purpurascens | purple milkweed | Apocynaceae | CT MA NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Asclepias quadrifolia | four-leaved milkweed | Apocynaceae | CT MA NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Asclepias syriaca | common milkweed | Apocynaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Asclepias tuberosa | butterfly milkweed | Apocynaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Asclepias variegata | red-ringed milkweed | Apocynaceae | CT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Asclepias verticillata | whorled milkweed | Apocynaceae | CT MA RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Asclepias viridiflora | green milkweed | Apocynaceae | CT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Asparagus officinalis | asparagus | Asparagaceae | CT MA ME NH RI VT | No | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Asperugo procumbens | madwort | Boraginaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Asperula arvensis | blue woodruff | Rubiaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Asplenium montanum | mountain spleenwort | Aspleniaceae | CT MA RI VT | Yes | Ferns | True ferns and moonworts | |
| Asplenium platyneuron | ebony spleenwort | Aspleniaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Asplenium rhizophyllum | walking fern, walking spleenwort | Aspleniaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Asplenium ruta-muraria | wall-rue spleenwort | Aspleniaceae | CT MA RI VT | Yes | Ferns | True ferns and moonworts | |
| Asplenium trichomanes | maidenhair spleenwort | Aspleniaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Asplenium viride | green spleenwort | Aspleniaceae | ME VT | Yes | Ferns | True ferns and moonworts | |
| Aster tataricus | Tatarian aster | Asteraceae | CT MA RI | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Astragalus alpinus | alpine milk-vetch | Fabaceae | ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Astragalus canadensis | Canada milk-vetch | Fabaceae | CT VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Astragalus contortuplicatus | Hungarian milk-vetch | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Astragalus eucosmus | elegant milk-vetch | Fabaceae | ME | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Astragalus glycyphyllos | licorice milk-vetch | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Astragalus robbinsii | Robbins' milk-vetch | Fabaceae | ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Astrantia major | greater masterwort | Apiaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Athyrium angustum | northern lady fern | Woodsiaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Athyrium asplenioides | southern lady fern | Woodsiaceae | CT MA RI | Yes | Ferns | True ferns and moonworts | |
| Athyrium nipponicum | Japanese painted lady fern | Woodsiaceae | RI | No | Ferns | True ferns and moonworts | |
| Atocion armeria | sweet-William-catchfly | Caryophyllaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Atriplex acadiensis | maritime orache | Amaranthaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Atriplex cristata | seabeach orache | Amaranthaceae | CT MA NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Atriplex glabriuscula | bracted orache | Amaranthaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Atriplex hortensis | garden orache | Amaranthaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Atriplex littoralis | linear-leaved orache | Amaranthaceae | CT MA ME NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Atriplex patula | spearscale orache | Amaranthaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Atriplex prostrata | hastate-leaved orache | Amaranthaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Atriplex rosea | red orache | Amaranthaceae | MA RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Atriplex sibirica | Siberian orache | Amaranthaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Atriplex subspicata | saline orache | Amaranthaceae | CT MA ME NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Atriplex tatarica | Tatarian orache | Amaranthaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Aureolaria flava | smooth false foxglove | Orobanchaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Aureolaria pedicularia | fern-leaved false foxglove | Orobanchaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Aureolaria virginica | downy false foxglove | Orobanchaceae | CT MA NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Aurinia saxatilis | rock goldentuft | Brassicaceae | CT MA NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Avena fatua | wild oat | Poaceae | CT MA ME NH VT | No | Grass-like plants | True grasses | |
| Avena sativa | oat | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Avena strigosa | lopsided oat | Poaceae | MA | No | Grass-like plants | True grasses | |
| Avenula pubescens | downy alpine oat grass | Poaceae | CT MA VT | No | Grass-like plants | True grasses | |
| Axyris amaranthoides | Russian-pigweed | Amaranthaceae | MA ME NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Azolla caroliniana | Carolina mosquito fern | Azollaceae | CT MA ME NH | Yes | Aquatic plants; Ferns | Water plants with leaves and stems; True ferns and moonworts | |
| Baccharis halimifolia | eastern false willow | Asteraceae | CT MA RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Ballota nigra | black-horehound | Lamiaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Balsamita major | costmary | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Baptisia australis | blue wild indigo | Fabaceae | CT MA NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Baptisia bracteata | long-bracted wild indigo | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Baptisia tinctoria | yellow wild indigo | Fabaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Barbarea orthoceras | American yellow-rocket | Brassicaceae | ME NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Barbarea stricta | upright yellow-rocket | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Barbarea verna | early yellow-rocket | Brassicaceae | CT MA ME RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Barbarea vulgaris | garden yellow-rocket | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Bartonia iodandra | purple screwstem | Gentianaceae | CT MA ME NH RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Bartonia paniculata | twining screwstem | Gentianaceae | CT MA RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Bartonia virginica | Virginia screwstem | Gentianaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Bassia hirsuta | hairy smotherweed | Amaranthaceae | CT MA NH RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Bassia hyssopifolia | five-horned smotherweed | Amaranthaceae | MA ME RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Beckmannia syzigachne | American slough grass | Poaceae | ME VT | Yes | Grass-like plants | True grasses | |
| Bellis perennis | lawn-daisy | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Benthamidia florida | flowering big-bracted-dogwood | Cornaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Benthamidia japonica | kousa big-bracted-dogwood | Cornaceae | CT | No | Woody Plants | Broad-leaved woody plants | |
| Berberis aquifolium | holly-leaved Oregon-grape | Berberidaceae | MA VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Berberis koreana | Korea barberry | Berberidaceae | VT | No | Woody Plants | Broad-leaved woody plants | |
| Berberis thunbergii | Japanese barberry | Berberidaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Berberis vulgaris | common barberry | Berberidaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Berteroa incana | hoary false alyssum | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Berteroa mutabilis | roadside false alyssum | Brassicaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Beta vulgaris | beet | Amaranthaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Betula alleghaniensis | yellow birch | Betulaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Betula cordifolia | heart-leaved paper birch | Betulaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Betula glandulosa | glandular birch | Betulaceae | ME NH | Yes | Woody Plants | Broad-leaved woody plants | |
| Betula lenta | cherry birch | Betulaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Betula minor | dwarf birch | Betulaceae | ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Betula nigra | river birch | Betulaceae | CT MA NH | Yes | Woody Plants | Broad-leaved woody plants | |
| Betula papyrifera | paper birch | Betulaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Betula pendula | European weeping birch | Betulaceae | CT MA VT | No | Woody Plants | Broad-leaved woody plants | |
| Betula populifolia | gray birch | Betulaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Betula pubescens | downy birch | Betulaceae | CT MA ME VT | No | Woody Plants | Broad-leaved woody plants | |
| Betula pumila | bog birch | Betulaceae | CT MA ME NH | Yes | Woody Plants | Broad-leaved woody plants | |
| Bidens alba | white beggar-ticks | Asteraceae | CT MA | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Bidens aristosa | midwestern beggar-ticks | Asteraceae | CT MA ME NH | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Bidens beckii | Beck's beggar-ticks, Beck's water-marigold | Asteraceae | CT MA ME NH RI VT | Yes | Aquatic plants; All other flowering non-woody plants | Water plants with leaves and stems; Daisies, goldenrods, and other Aster family plants | |
| Bidens bipinnata | Spanish needles beggar-ticks | Asteraceae | CT MA | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Bidens cernua | nodding beggar-ticks | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Bidens connata | purple-stemmed beggar-ticks | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Bidens discoidea | small beggar-ticks | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Bidens eatonii | Eaton's beggar-ticks | Asteraceae | CT MA ME | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Bidens frondosa | Devil's beggar-ticks | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Bidens hyperborea | northern beggar-ticks | Asteraceae | MA ME NH | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Bidens laevis | smooth beggar-ticks | Asteraceae | CT MA NH RI | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Bidens pilosa | hairy beggar-ticks | Asteraceae | CT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Bidens polylepis | Ozark beggar-ticks | Asteraceae | MA RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Bidens tenuisecta | slim-lobed beggar-ticks | Asteraceae | MA | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Bidens trichosperma | crowned beggar-ticks | Asteraceae | CT MA RI | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Bidens tripartita | three-lobed beggar-ticks | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Bidens vulgata | tall beggar-ticks | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Bifora radians | wild bishop | Apiaceae | RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Bistorta officinalis | meadow bistort | Polygonaceae | MA ME | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Bistorta vivipara | alpine bistort | Polygonaceae | ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Blephilia ciliata | downy wood-mint | Lamiaceae | CT MA VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Blephilia hirsuta | hairy wood-mint | Lamiaceae | CT MA VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Boechera canadensis | sicklepod rockcress | Brassicaceae | CT MA NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Boechera grahamii | Graham's rockcress | Brassicaceae | VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Boechera laevigata | smooth rockcress | Brassicaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Boechera missouriensis | green rockcress | Brassicaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Boechera stricta | Canada rockcress | Brassicaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Boehmeria cylindrica | small-spiked false nettle | Urticaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Bolboschoenus fluviatilis | river tuber-bulrush | Cyperaceae | Yes | Grass-like plants | All other grass-like plants | ||
| Bolboschoenus glaucus | glaucous tuber-bulrush | Cyperaceae | No | Grass-like plants | All other grass-like plants | ||
| Bolboschoenus maritimus | saltmarsh tuber-bulrush | Cyperaceae | Yes | Grass-like plants | All other grass-like plants | ||
| Bolboschoenus novae-angliae | New England tuber-bulrush | Cyperaceae | CT MA ME RI | Yes | Grass-like plants | All other grass-like plants | |
| Bolboschoenus robustus | sea-coast tuber-bulrush | Cyperaceae | CT MA ME NH RI | Yes | Grass-like plants | All other grass-like plants | |
| Boltonia asteroides | white doll's-daisy | Asteraceae | CT MA ME RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Borago officinalis | borage | Boraginaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Botrychium angustisegmentum | narrow triangle moonwort | Ophioglossaceae | Yes | Ferns | True ferns and moonworts | ||
| Botrychium ascendens | upswept moonwort | Ophioglossaceae | VT | Yes | Ferns | True ferns and moonworts | |
| Botrychium campestre | prairie moonwort | Ophioglossaceae | VT | Yes | Ferns | True ferns and moonworts | |
| Botrychium dissectum | dissected grapefern | Ophioglossaceae | Yes | Ferns | True ferns and moonworts | ||
| Botrychium lunaria | common moonwort | Ophioglossaceae | ME VT | Yes | Ferns | True ferns and moonworts | |
| Botrychium matricariifolium | daisy-leaved moonwort | Ophioglossaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Botrychium minganense | Mingan moonwort | Ophioglossaceae | ME VT | Yes | Ferns | True ferns and moonworts | |
| Botrychium multifidum | leathery grapefern | Ophioglossaceae | Yes | Ferns | True ferns and moonworts | ||
| Botrychium oneidense | blunt-lobed grapefern | Ophioglossaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Botrychium pallidum | pale moonwort | Ophioglossaceae | ME | Yes | Ferns | True ferns and moonworts | |
| Botrychium rugulosum | St. Lawrence grapefern | Ophioglossaceae | CT VT | Yes | Ferns | True ferns and moonworts | |
| Botrychium simplex | least moonwort | Ophioglossaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Botrychium tenebrosum | swamp moonwort | Ophioglossaceae | CT MA ME NH VT | Yes | Ferns | True ferns and moonworts | |
| Botrychium virginianum | rattlesnake fern | Ophioglossaceae | Yes | Ferns | True ferns and moonworts | ||
| Bouteloua curtipendula | sideoats grama | Poaceae | CT ME | Yes | Grass-like plants | True grasses | |
| Bouteloua gracilis | blue grama | Poaceae | MA ME VT | No | Grass-like plants | True grasses | |
| Bouteloua repens | slender grama | Poaceae | MA ME | Yes | Grass-like plants | True grasses | |
| Bouteloua rigidiseta | Texas grama | Poaceae | MA | Yes | Grass-like plants | True grasses | |
| Bouteloua simplex | mat grama | Poaceae | ME | Yes | Grass-like plants | True grasses | |
| Brachyelytrum aristosum | northern long-awned wood grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Brachyelytrum erectum | southern long-awned wood grass | Poaceae | CT MA NH RI VT | Yes | Grass-like plants | True grasses | |
| Brachypodium pinnatum | heath false brome | Poaceae | MA | No | Grass-like plants | True grasses | |
| Brasenia schreberi | water-shield | Nymphaeaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Brassica juncea | Chinese mustard | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Brassica napus | turnip | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Brassica nigra | black mustard | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Brassica oleracea | cabbage | Brassicaceae | CT MA RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Brassica rapa | rape | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Braya humilis | alpine northern-rockcress | Brassicaceae | VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Briza media | perennial quaking grass | Poaceae | CT MA ME NH VT | No | Grass-like plants | True grasses | |
| Briza minor | little quaking grass | Poaceae | CT | No | Grass-like plants | True grasses | |
| Bromus arvensis | field brome | Poaceae | CT MA ME NH | No | Grass-like plants | True grasses | |
| Bromus briziformis | rattlesnake brome | Poaceae | CT MA VT | No | Grass-like plants | True grasses | |
| Bromus ciliatus | fringed brome | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Bromus commutatus | meadow brome | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Bromus erectus | upright brome | Poaceae | CT MA ME VT | No | Grass-like plants | True grasses | |
| Bromus hordeaceus | soft brome | Poaceae | CT MA ME NH RI | No | Grass-like plants | True grasses | |
| Bromus inermis | smooth brome | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Bromus japonicus | Japanese brome | Poaceae | CT MA ME NH VT | No | Grass-like plants | True grasses | |
| Bromus kalmii | Kalm's brome | Poaceae | CT MA ME NH VT | Yes | Grass-like plants | True grasses | |
| Bromus latiglumis | flanged brome | Poaceae | CT MA ME NH VT | Yes | Grass-like plants | True grasses | |
| Bromus lepidus | slender soft brome | Poaceae | MA | No | Grass-like plants | True grasses | |
| Bromus marginatus | large mountain brome | Poaceae | CT MA ME NH | Yes | Grass-like plants | True grasses | |
| Bromus pubescens | hairy wood brome | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Bromus racemosus | bald brome | Poaceae | RI VT | No | Grass-like plants | True grasses | |
| Bromus rigidus | ripgut brome | Poaceae | MA | No | Grass-like plants | True grasses | |
| Bromus rubens | foxtail brome | Poaceae | MA | No | Grass-like plants | True grasses | |
| Bromus secalinus | rye brome | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Bromus squarrosus | corn brome | Poaceae | CT VT | No | Grass-like plants | True grasses | |
| Bromus sterilis | poverty brome | Poaceae | CT MA RI | No | Grass-like plants | True grasses | |
| Bromus tectorum | cheat brome, cheatgrass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Broussonetia papyrifera | paper-mulberry | Moraceae | CT MA RI | No | Woody Plants | Broad-leaved woody plants | |
| Browallia americana | Jamaican-forget-me-not | Solanaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Buddleja davidii | orange-eye butterfly-bush | Scrophulariaceae | CT MA RI | No | Woody Plants | Broad-leaved woody plants | |
| Buglossoides arvensis | corn-gromwell | Boraginaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Bulbostylis capillaris | tufted hair-sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Bunias orientalis | Turkish warty-cabbage | Brassicaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Bupleurum lancifolium | lance-leaved thorough-wax | Apiaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Bupleurum odontites | round-leaved thorough-wax | Apiaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Bupleurum rotundifolium | narrow-leaved thorough-wax | Apiaceae | NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Butomus umbellatus | flowering-rush | Butomaceae | CT MA ME VT | No | Aquatic plants; Orchids and related plants | Water plants with leaves and stems; Irises, lilies, and other "monocots" | |
| Cabomba caroliniana | Carolina fanwort | Nymphaeaceae | CT MA ME NH RI | Yes | Aquatic plants | Water plants with leaves and stems | |
| Cakile edentula | American sea-rocket | Brassicaceae | CT MA ME NH RI | Yes | |||
| Calamagrostis canadensis | bluejoint, Canada reed grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Calamagrostis cinnoides | Nuttall's reed grass | Poaceae | CT MA ME NH RI | Yes | Grass-like plants | True grasses | |
| Calamagrostis epigejos | feathertop reed grass | Poaceae | MA RI VT | No | Grass-like plants | True grasses | |
| Calamagrostis pickeringii | Pickering's reed grass | Poaceae | MA ME NH VT | Yes | Grass-like plants | True grasses | |
| Calamagrostis stricta | neglected reed grass | Poaceae | CT MA ME NH VT | Yes | Grass-like plants | True grasses | |
| Calandrinia ciliata | fringed redmaids | Portulacaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Calendula officinalis | pot-marigold | Asteraceae | CT MA ME NH | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Calla palustris | water arum, wild calla | Araceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Callistephus chinensis | Chinese-aster | Asteraceae | CT MA ME | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Callitriche hermaphroditica | autumn water-starwort | Plantaginaceae | CT VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Callitriche heterophylla | greater water-starwort | Plantaginaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Callitriche palustris | vernal water-starwort | Plantaginaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Callitriche stagnalis | pond water-starwort | Plantaginaceae | CT MA ME | No | Aquatic plants | Water plants with leaves and stems | |
| Callitriche terrestris | terrestrial water-starwort | Plantaginaceae | CT MA ME | Yes | Aquatic plants | Water plants with leaves and stems | |
| Calluna vulgaris | heather | Ericaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Calopogon tuberosus | tuberous grass-pink | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Calotis cuneifolia | Australian wedgeleaf | Asteraceae | MA | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Caltha palustris | marsh-marigold | Ranunculaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Calycanthus floridus | eastern sweetshrub | Calycanthaceae | CT MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Calypso bulbosa | fairy-slipper | Orchidaceae | ME NH VT | Yes | Orchids and related plants | Orchids | |
| Calystegia pubescens | hairy false bindweed | Convolvulaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Calystegia sepium | hedge false bindweed | Convolvulaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Calystegia silvatica | short-stalked false bindweed | Convolvulaceae | CT MA RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Calystegia spithamaea | upright false bindweed | Convolvulaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Camelina microcarpa | small-seeded false flax | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Camelina sativa | large-seeded false flax | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Camissonia bistorta | California suncup | Onagraceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Camissonia campestris | Mojave suncup | Onagraceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Campanula aparinoides | marsh bellflower | Campanulaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Campanula carpatica | tussock bellflower | Campanulaceae | CT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Campanula divaricata | southern bellflower | Campanulaceae | CT NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Campanula glomerata | clustered bellflower | Campanulaceae | MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Campanula lanata | woolly bellflower | Campanulaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Campanula latifolia | giant bellflower | Campanulaceae | ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Campanula patula | spreading bellflower | Campanulaceae | CT MA NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Campanula persicifolia | peach-leaved bellflower | Campanulaceae | CT MA VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Campanula punctata | spotted bellflower | Campanulaceae | CT NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Campanula rapunculoides | creeping bellflower | Campanulaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Campanula rotundifolia | Scotch bellflower | Campanulaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Campanula trachelium | nettle-leaved bellflower | Campanulaceae | MA VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Campsis radicans | trumpet-creeper | Bignoniaceae | CT MA NH | Yes | Woody Plants | Broad-leaved woody plants | |
| Cannabis sativa | hemp | Cannabaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Capnoides sempervirens | pink-corydalis | Papaveraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Capsella bursa-pastoris | shepherd's-purse | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Caragana arborescens | Siberian pea shrub | Fabaceae | MA ME VT | No | Woody Plants | Broad-leaved woody plants | |
| Cardamine bellidifolia | alpine bitter-cress | Brassicaceae | ME NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cardamine bulbosa | bulbous bitter-cress | Brassicaceae | CT MA NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cardamine concatenata | cut-leaved toothwort | Brassicaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cardamine dentata | white cuckoo bitter-cress | Brassicaceae | CT MA VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cardamine diphylla | two-leaved toothwort | Brassicaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cardamine douglassii | pink bitter-cress | Brassicaceae | CT MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cardamine flexuosa | wavy bitter-cress | Brassicaceae | CT MA RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cardamine hirsuta | hairy bitter-cress | Brassicaceae | CT MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cardamine impatiens | narrow-leaved bitter-cress | Brassicaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cardamine incisa | Eames' toothwort | Brassicaceae | CT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cardamine longii | Long's bitter-cress | Brassicaceae | CT MA ME NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cardamine maxima | large toothwort | Brassicaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cardamine parviflora | small-flowered bitter-cress | Brassicaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cardamine pensylvanica | Pennsylvania bitter-cress | Brassicaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cardamine pratensis | pink cuckoo bitter-cress | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cardiospermum halicacabum | balloon-vine | Sapindaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Carduus acanthoides | spiny plumeless-thistle | Asteraceae | CT MA ME RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Carduus crispus | curly plumeless-thistle | Asteraceae | RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Carduus nutans | nodding plumeless-thistle | Asteraceae | CT MA NH RI | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Carex abscondita | thicket sedge | Cyperaceae | CT MA RI | Yes | Grass-like plants | Sedges | |
| Carex acutiformis | lesser pond sedge | Cyperaceae | CT MA | No | Grass-like plants | Sedges | |
| Carex adusta | swarthy sedge | Cyperaceae | ME NH | Yes | Grass-like plants | Sedges | |
| Carex aestivalis | summer sedge | Cyperaceae | CT MA NH VT | Yes | Grass-like plants | Sedges | |
| Carex alata | broad-winged sedge | Cyperaceae | CT MA NH RI | Yes | Grass-like plants | Sedges | |
| Carex albicans | white-tinged sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex albolutescens | green-white sedge | Cyperaceae | CT MA NH | Yes | Grass-like plants | Sedges | |
| Carex albursina | white bear sedge | Cyperaceae | CT MA NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex alopecoidea | fox-tail sedge | Cyperaceae | CT MA ME VT | Yes | Grass-like plants | Sedges | |
| Carex amphibola | eastern narrow-leaved sedge | Cyperaceae | CT MA | Yes | Grass-like plants | Sedges | |
| Carex annectens | yellow-fruited sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex appalachica | Appalachian sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex aquatilis | water sedge | Cyperaceae | CT MA ME RI VT | Yes | Grass-like plants | Sedges | |
| Carex arcta | northern cluster sedge | Cyperaceae | ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex arctata | drooping woodland sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex arctogena | capitate sedge | Cyperaceae | NH | Yes | Grass-like plants | Sedges | |
| Carex argyrantha | silvery-flowered sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex atherodes | wheat sedge | Cyperaceae | ME NH VT | Yes and no (some introduced) | Grass-like plants | Sedges | |
| Carex atlantica | prickly bog sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex atratiformis | scabrous black sedge | Cyperaceae | ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex aurea | golden-fruited sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex backii | Back's sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex baileyi | Bailey's sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex barrattii | Barratt's sedge | Cyperaceae | CT | Yes | Grass-like plants | Sedges | |
| Carex bebbii | Bebb's sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex bicknellii | Bicknell's sedge | Cyperaceae | CT MA ME RI VT | Yes | Grass-like plants | Sedges | |
| Carex bigelowii | Bigelow's sedge | Cyperaceae | ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex billingsii | Billings' sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex blanda | eastern woodland sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex brevior | short-beaked sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex bromoides | brome-like sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex brunnea | greater brown sedge | Cyperaceae | MA | No | Grass-like plants | Sedges | |
| Carex brunnescens | brownish sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex bullata | button sedge | Cyperaceae | CT MA ME NH RI | Yes | Grass-like plants | Sedges | |
| Carex bushii | Bush's sedge | Cyperaceae | CT MA ME VT | Yes | Grass-like plants | Sedges | |
| Carex buxbaumii | brown bog sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex canescens | hoary sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex capillaris | hair-like sedge | Cyperaceae | ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex caryophyllea | vernal sedge | Cyperaceae | MA ME | No | Grass-like plants | Sedges | |
| Carex castanea | chestnut sedge | Cyperaceae | CT MA ME NH VT | Grass-like plants | Sedges | ||
| Carex cephaloidea | thin-leaved sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex cephalophora | oval-headed sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex chordorrhiza | rope-root sedge | Cyperaceae | MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex collinsii | Collins' sedge | Cyperaceae | CT RI | Yes | Grass-like plants | Sedges | |
| Carex communis | fibrous-rooted sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex comosa | bearded sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex conoidea | open-field sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex crawei | Crawe's sedge | Cyperaceae | CT ME | Yes | Grass-like plants | Sedges | |
| Carex crawfordii | Crawford's sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex crinita | fringed sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex cristatella | crested sedge | Cyperaceae | CT MA NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex cryptolepis | northeastern sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex cumulata | clustered sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex davisii | Davis' sedge | Cyperaceae | CT MA VT | Yes | Grass-like plants | Sedges | |
| Carex debilis | white-edged sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex deflexa | northern sedge | Cyperaceae | MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex deweyana | round-fruited short-scaled sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex diandra | lesser tussock sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex digitalis | slender woodland sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex disperma | soft-leaved sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex eburnea | bristle-leaved sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex echinata | star sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex echinodes | prickly quill sedge | Cyperaceae | VT | Yes | Grass-like plants | Sedges | |
| Carex emoryi | Emory's sedge | Cyperaceae | CT MA | Yes | Grass-like plants | Sedges | |
| Carex exilis | meager sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex festucacea | fescue sedge | Cyperaceae | CT MA ME NH RI | Yes | Grass-like plants | Sedges | |
| Carex flacca | glaucous sedge | Cyperaceae | CT VT | No | Grass-like plants | Sedges | |
| Carex flava | yellow-green sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex foenea | straw sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex folliculata | northern long sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex formosa | handsome sedge | Cyperaceae | CT MA VT | Yes | Grass-like plants | Sedges | |
| Carex garberi | elk sedge | Cyperaceae | ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex glaucodea | blue sedge | Cyperaceae | CT MA NH VT | Yes | Grass-like plants | Sedges | |
| Carex gracilescens | slender loose-flowered sedge | Cyperaceae | CT MA VT | Yes | Grass-like plants | Sedges | |
| Carex gracillima | graceful sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex granularis | limestone-meadow sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex grayi | Gray's sedge | Cyperaceae | CT MA VT | Yes | Grass-like plants | Sedges | |
| Carex grisea | inflated narrow-leaved sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex gynandra | nodding sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex gynocrates | northern bog sedge | Cyperaceae | ME | Yes | Grass-like plants | Sedges | |
| Carex haydenii | Hayden's sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex hirsutella | hirsute sedge | Cyperaceae | CT MA RI VT | Yes | Grass-like plants | Sedges | |
| Carex hirta | hammer sedge | Cyperaceae | CT MA ME VT | No | Grass-like plants | Sedges | |
| Carex hirtifolia | pubescent sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex hitchcockiana | Hitchcock's sedge | Cyperaceae | CT MA NH VT | Yes | Grass-like plants | Sedges | |
| Carex hormathodes | marsh straw sedge | Cyperaceae | CT MA ME NH RI | Yes | Grass-like plants | Sedges | |
| Carex houghtoniana | Houghton's sedge | Cyperaceae | ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex hystericina | porcupine sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex interior | inland sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex intumescens | greater bladder sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex kobomugi | Japanese sedge | Cyperaceae | MA RI | No | Grass-like plants | Sedges | |
| Carex lacustris | lakeside sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex laevivaginata | smooth-sheathed sedge | Cyperaceae | CT MA RI VT | Yes | Grass-like plants | Sedges | |
| Carex lasiocarpa | woolly-fruited sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex laxiculmis | spreading sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex laxiflora | broad loose-flowered sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex lenticularis | lake shore sedge | Cyperaceae | MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex leptalea | bristly-stalk sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex leptonervia | nerveless woodland sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex limosa | mud sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex livida | livid sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex longii | Long's sedge | Cyperaceae | CT MA ME RI VT | Yes | Grass-like plants | Sedges | |
| Carex lucorum | Blue Ridge sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex lupuliformis | false hop sedge | Cyperaceae | CT MA VT | Yes | Grass-like plants | Sedges | |
| Carex lupulina | hop sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex lurida | sallow sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex mackenziei | Mackenzie's sedge | Cyperaceae | ME | Yes | Grass-like plants | Sedges | |
| Carex magellanica | boreal bog sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex meadii | Mead's sedge | Cyperaceae | RI | Yes | Grass-like plants | Sedges | |
| Carex media | closed-headed sedge | Cyperaceae | ME | Yes | Grass-like plants | Sedges | |
| Carex merritt-fernaldii | Merritt Fernald's sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex mesochorea | midland sedge | Cyperaceae | CT MA | Yes | Grass-like plants | Sedges | |
| Carex michauxiana | Michaux's sedge | Cyperaceae | MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex mitchelliana | Mitchell's sedge | Cyperaceae | MA RI | Yes | Grass-like plants | Sedges | |
| Carex molesta | troublesome sedge | Cyperaceae | CT MA NH VT | Yes | Grass-like plants | Sedges | |
| Carex muehlenbergii | Muhlenberg's sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex nigra | smooth black sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex nigromarginata | black-edged sedge | Cyperaceae | CT | Yes | Grass-like plants | Sedges | |
| Carex normalis | greater straw sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex novae-angliae | New England sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex oklahomensis | Oklahoma sedge | Cyperaceae | ME | Yes | Grass-like plants | Sedges | |
| Carex oligocarpa | rich woods sedge | Cyperaceae | CT MA VT | Yes | Grass-like plants | Sedges | |
| Carex oligosperma | few-seeded sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex ormostachya | necklace spike sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex oronensis | Orono sedge | Cyperaceae | ME | Yes | Grass-like plants | Sedges | |
| Carex ovalis | oval sedge | Cyperaceae | MA ME NH | Yes and no (some introduced) | Grass-like plants | Sedges | |
| Carex paleacea | chaffy sedge | Cyperaceae | MA ME NH | Yes | Grass-like plants | Sedges | |
| Carex pallescens | pale sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex panicea | grass-like sedge | Cyperaceae | CT MA ME NH RI | No | Grass-like plants | Sedges | |
| Carex pauciflora | few-flowered sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex peckii | Peck's sedge | Cyperaceae | MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex pedunculata | long-stalked sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex pellita | woolly sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex pensylvanica | Pennsylvania sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex plantaginea | plantain-leaved sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex platyphylla | broad-leaved sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex polymorpha | variable sedge | Cyperaceae | CT MA ME NH RI | Yes | Grass-like plants | Sedges | |
| Carex praegracilis | clustered field sedge, freeway sedge | Cyperaceae | ME VT | Yes | Grass-like plants | Sedges | |
| Carex prairea | prairie sedge | Cyperaceae | CT MA ME VT | Yes | Grass-like plants | Sedges | |
| Carex prasina | drooping sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex praticola | northern meadow sedge | Cyperaceae | ME | Yes | Grass-like plants | Sedges | |
| Carex projecta | necklace sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex pseudocyperus | cypress-like sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex radiata | eastern star sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex rariflora | loose-flowered alpine sedge | Cyperaceae | ME | Yes | Grass-like plants | Sedges | |
| Carex recta | estuary sedge | Cyperaceae | ME | Yes | Grass-like plants | Sedges | |
| Carex retroflexa | reflexed sedge | Cyperaceae | CT MA NH RI | Yes | Grass-like plants | Sedges | |
| Carex retrorsa | retrorse sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex reznicekii | Reznicek's sedge | Cyperaceae | CT RI | Yes | Grass-like plants | Sedges | |
| Carex richardsonii | Richardson's sedge | Cyperaceae | VT | Yes | Grass-like plants | Sedges | |
| Carex rosea | rosy sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex rostrata | beaked sedge | Cyperaceae | ME NH | Yes | Grass-like plants | Sedges | |
| Carex saxatilis | russet sedge | Cyperaceae | ME | Yes | Grass-like plants | Sedges | |
| Carex scabrata | eastern rough sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex schweinitzii | Schweinitz's sedge | Cyperaceae | CT MA RI VT | Yes | Grass-like plants | Sedges | |
| Carex scirpoidea | Canadian single-spike sedge | Cyperaceae | ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex scoparia | pointed broom sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex seorsa | weak stellate sedge | Cyperaceae | CT MA NH RI | Yes | Grass-like plants | Sedges | |
| Carex siccata | dry land sedge | Cyperaceae | MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex silicea | sea-beach sedge | Cyperaceae | CT MA ME NH RI | Yes | Grass-like plants | Sedges | |
| Carex sparganioides | bur-reed sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex spicata | prickly sedge | Cyperaceae | CT MA ME NH RI VT | No | Grass-like plants | Sedges | |
| Carex sprengelii | long-beaked sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex squarrosa | squarrose sedge | Cyperaceae | CT MA | Yes | Grass-like plants | Sedges | |
| Carex sterilis | dioecious sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex stipata | awl-fruited sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex straminea | eastern straw sedge | Cyperaceae | CT MA RI | Yes | Grass-like plants | Sedges | |
| Carex striata | Walter's sedge | Cyperaceae | MA NH RI | Yes | Grass-like plants | Sedges | |
| Carex striatula | lined sedge | Cyperaceae | CT | Yes | Grass-like plants | Sedges | |
| Carex stricta | tussock sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex styloflexa | bent sedge | Cyperaceae | CT RI | Yes | Grass-like plants | Sedges | |
| Carex swanii | Swan's sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex sychnocephala | many-headed sedge | Cyperaceae | ME | Yes | Grass-like plants | Sedges | |
| Carex tenera | delicate quill sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex tenuiflora | sparse-flowered sedge | Cyperaceae | ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex tetanica | rigid sedge | Cyperaceae | CT MA NH | Yes | Grass-like plants | Sedges | |
| Carex tincta | tinged sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex tonsa | shaved sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex torta | twisted sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex tribuloides | blunt broom sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex trichocarpa | hairy-fruited sedge | Cyperaceae | CT MA NH VT | Yes | Grass-like plants | Sedges | |
| Carex trisperma | three-seeded sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex tuckermanii | Tuckerman's sedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex typhina | cattail sedge | Cyperaceae | CT MA ME VT | Yes | Grass-like plants | Sedges | |
| Carex umbellata | parasol sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex utriculata | swollen-beaked sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex vacillans | swinging sedge | Cyperaceae | MA ME | No | Grass-like plants | Sedges | |
| Carex vaginata | sheathed sedge | Cyperaceae | ME VT | Yes | Grass-like plants | Sedges | |
| Carex vesicaria | lesser bladder sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex vestita | velvet sedge | Cyperaceae | CT MA ME NH RI | Yes | Grass-like plants | Sedges | |
| Carex virescens | ribbed sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex viridula | little green sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex vulpinoidea | common fox sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | Sedges | |
| Carex wiegandii | Wiegand's sedge | Cyperaceae | MA ME NH VT | Yes | Grass-like plants | Sedges | |
| Carex willdenowii | Willdenow's sedge | Cyperaceae | CT MA VT | Yes | Grass-like plants | Sedges | |
| Carpinus caroliniana | American hornbeam | Betulaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Carthamus lanatus | woolly safflower-thistle | Asteraceae | MA | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Carthamus tinctorius | common safflower-thistle | Asteraceae | MA | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Carum carvi | caraway | Apiaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Carya cordiformis | bitternut hickory | Juglandaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Carya glabra | pignut hickory | Juglandaceae | CT MA NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Carya laciniosa | shellbark hickory | Juglandaceae | MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Carya ovata | shagbark hickory | Juglandaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Carya tomentosa | mockernut hickory | Juglandaceae | Yes | Woody Plants | Broad-leaved woody plants | ||
| Castanea dentata | American chestnut | Fagaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Castanea mollissima | Chinese chestnut | Fagaceae | CT MA RI | No | Woody Plants | Broad-leaved woody plants | |
| Castanea pumila | dwarf chestnut | Fagaceae | MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Castanea sativa | Spanish chestnut | Fagaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Castilleja coccinea | scarlet painted-cup | Orobanchaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Castilleja exserta | purple painted-cup | Orobanchaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Castilleja septentrionalis | northern painted-cup | Orobanchaceae | ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Catalpa bignonioides | southern catalpa | Bignoniaceae | CT MA ME VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Catalpa ovata | Chinese catalpa | Bignoniaceae | CT MA VT | No | Woody Plants | Broad-leaved woody plants | |
| Catalpa speciosa | northern catalpa | Bignoniaceae | CT MA ME NH | No | Woody Plants | Broad-leaved woody plants | |
| Caulophyllum giganteum | early blue cohosh | Berberidaceae | CT MA NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Caulophyllum thalictroides | blue cohosh | Berberidaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ceanothus americanus | New Jersey redroot, New Jersey tea | Rhamnaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Ceanothus herbaceus | prairie redroot | Rhamnaceae | MA VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Celastrus orbiculatus | Asian bittersweet, Asiatic bittersweet | Celastraceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Celastrus scandens | American bittersweet | Celastraceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Celosia cristata | crested cock's-comb | Amaranthaceae | CT MA RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Celtis occidentalis | common hackberry | Cannabaceae | CT MA NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Cenchrus longispinus | long-spined sandbur | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Cenchrus spinifex | coastal sandbur | Poaceae | MA ME NH VT | Yes | Grass-like plants | True grasses | |
| Centaurea benedicta | blessed knapweed | Asteraceae | CT MA | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Centaurea calcitrapa | purple knapweed | Asteraceae | MA | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Centaurea cyanus | garden knapweed | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Centaurea diffusa | white knapweed | Asteraceae | CT MA NH RI | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Centaurea jacea | brown knapweed | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Centaurea melitensis | Maltese knapweed | Asteraceae | MA | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Centaurea montana | mountain knapweed | Asteraceae | ME NH VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Centaurea nigra | black knapweed | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Centaurea nigrescens | short-fringed knapweed | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Centaurea phrygia | wig knapweed | Asteraceae | VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Centaurea scabiosa | greater knapweed | Asteraceae | CT ME NH | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Centaurea solstitialis | yellow knapweed | Asteraceae | CT MA NH RI | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Centaurea stoebe | spotted knapweed | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Centaurium erythraea | European centaury | Gentianaceae | MA VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Centaurium pulchellum | branched centaury | Gentianaceae | CT MA ME VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Centipeda minima | spreading-sneezeweed | Asteraceae | MA | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Cephalanthus occidentalis | common buttonbush | Rubiaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Cephalaria gigantea | yellow giant-scabious | Caprifoliaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Cerastium arvense | field chickweed | Caryophyllaceae | CT MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Cerastium diffusum | four-stamened chickweed | Caryophyllaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Cerastium fontanum | mouse-ear chickweed | Caryophyllaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Cerastium glomeratum | sticky chickweed | Caryophyllaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Cerastium nutans | nodding chickweed | Caryophyllaceae | CT MA VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Cerastium pumilum | European chickweed | Caryophyllaceae | CT MA ME | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Cerastium semidecandrum | five-stamened chickweed | Caryophyllaceae | CT MA NH RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Cerastium strictum | American field chickweed | Caryophyllaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Cerastium tomentosum | tomentose chickweed | Caryophyllaceae | MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Ceratophyllum demersum | common hornwort, coontail | Ceratophyllaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Ceratophyllum echinatum | spineless hornwort | Ceratophyllaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Cercidiphyllum japonicum | Katsura-tree | Cercidiphyllaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Cercis canadensis | redbud | Fabaceae | CT MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Chaenactis glabriuscula | yellow pincushion | Asteraceae | MA | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Chaenomeles japonica | Japanese flowering-quince | Rosaceae | VT | No | Woody Plants | Broad-leaved woody plants | |
| Chaenomeles speciosa | common flowering-quince | Rosaceae | CT MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Chaenorhinum minus | dwarf-snapdragon | Plantaginaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Chamaecrista fasciculata | partridge sensitive-pea | Fabaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Chamaecrista nictitans | wild sensitive-pea | Fabaceae | CT MA NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Chamaecyparis thyoides | Atlantic white cedar | Cupressaceae | CT MA ME NH RI | Yes | Woody Plants | Needle-leaved woody plants | |
| Chamaedaphne calyculata | leatherleaf | Ericaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Chamaelirium luteum | devil's bit | Melanthiaceae | CT MA | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Chamaepericlymenum canadense | bunchberry, Canada dwarf-dogwood | Cornaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Chamerion angustifolium | narrow-leaved fireweed | Onagraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cheilanthes lanosa | hairy lip fern | Pteridaceae | CT | Yes | Ferns | True ferns and moonworts | |
| Chelidonium majus | greater celandine | Papaveraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Chelone glabra | white turtlehead | Plantaginaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Chelone lyonii | pink turtlehead | Plantaginaceae | CT MA ME | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Chelone obliqua | red turtlehead | Plantaginaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Chenopodium album | lambsquarters, white goosefoot | Amaranthaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Chenopodium berlandieri | pit-seeded goosefoot | Amaranthaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Chenopodium bonus-henricus | perennial goosefoot | Amaranthaceae | CT MA ME NH RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Chenopodium capitatum | strawberry-blite | Amaranthaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Chenopodium foggii | Fogg's goosefoot | Amaranthaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Chenopodium foliosum | leafy goosefoot | Amaranthaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Chenopodium glaucum | oak-leaved goosefoot | Amaranthaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Chenopodium leptophyllum | narrow-leaved goosefoot | Amaranthaceae | ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Chenopodium murale | nettle-leaved goosefoot | Amaranthaceae | CT MA ME RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Chenopodium polyspermum | many-seeded goosefoot | Amaranthaceae | MA ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Chenopodium pratericola | desert goosefoot | Amaranthaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Chenopodium rubrum | red goosefoot | Amaranthaceae | CT MA ME NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Chenopodium simplex | giant-seeded goosefoot | Amaranthaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Chenopodium standleyanum | Standley's goosefoot | Amaranthaceae | CT MA VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Chenopodium strictum | oval-seeded goosefoot | Amaranthaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Chenopodium urbicum | city goosefoot | Amaranthaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Chimaphila maculata | pipsissewa, spotted wintergreen | Ericaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants; Woody Plants | Other herbaceous, flowering plants with opposite, whorled or no leaves; Broad-leaved woody plants | |
| Chimaphila umbellata | noble prince's-pine, pipsissewa | Ericaceae | CT MA ME NH RI VT | Yes | Woody Plants; All other flowering non-woody plants | Broad-leaved woody plants; Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Chionanthus virginicus | white fringe-tree | Oleaceae | MA RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Chionodoxa forbesii | Forbes' glory-of-the-snow | Hyacinthaceae | VT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Chionodoxa luciliae | Lucile's glory-of-the-snow | Hyacinthaceae | MA | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Chloris cucullata | hooded windmill-grass | Poaceae | ME | Yes | Grass-like plants | True grasses | |
| Chloris gayana | Rhodes windmill-grass | Poaceae | MA | No | Grass-like plants | True grasses | |
| Chloris verticillata | tumble windmill-grass | Poaceae | CT MA | Yes | Grass-like plants | True grasses | |
| Chloris virgata | feather windmill-grass | Poaceae | MA ME | Yes | Grass-like plants | True grasses | |
| Chorispora tenella | crossflower | Brassicaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Chorizanthe pungens | Monterey spineflower | Polygonaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Chrysanthemum morifolium | florist's daisy | Asteraceae | MA | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Chrysopsis mariana | Maryland golden-aster | Asteraceae | RI | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Chrysosplenium americanum | golden-saxifrage | Saxifragaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cicer arietinum | chick-pea | Fabaceae | CT MA NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Cichorium endivia | cultivated endive | Asteraceae | CT ME | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Cichorium intybus | chicory | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Cicuta bulbifera | bulblet-bearing water-hemlock | Apiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cicuta maculata | spotted water-hemlock | Apiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cinna arundinacea | sweet wood-reed | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Cinna latifolia | slender wood-reed | Poaceae | CT MA ME NH VT | Yes | Grass-like plants | True grasses | |
| Circaea alpina | small enchanter's-nightshade | Onagraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Circaea canadensis | broad-leaved enchanter's-nightshade | Onagraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Cirsium altissimum | tall thistle | Asteraceae | CT MA VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Cirsium arvense | creeping thistle | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Cirsium discolor | field thistle | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Cirsium flodmanii | Flodman's thistle | Asteraceae | VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Cirsium horridulum | yellow thistle | Asteraceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Cirsium muticum | swamp thistle | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Cirsium palustre | marsh thistle | Asteraceae | MA NH | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Cirsium pumilum | pasture thistle | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Cirsium vulgare | common thistle | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Citrullus lanatus | watermelon | Cucurbitaceae | CT MA ME RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cladium mariscoides | smooth saw-sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Cladrastis kentukea | Kentucky yellow-wood | Fabaceae | CT MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Clarkia pulchella | elk horn clarkia | Onagraceae | CT MA VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Clarkia rhomboidea | common clarkia | Onagraceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Claytonia caroliniana | Carolina spring-beauty | Portulacaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Claytonia sibirica | Siberian spring-beauty | Portulacaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Claytonia virginica | Virginia spring-beauty | Portulacaceae | CT MA RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Clematis florida | Asian virgin's-bower | Ranunculaceae | CT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Clematis occidentalis | purple virgin's-bower | Ranunculaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Clematis recta | ground virgin's-bower | Ranunculaceae | NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Clematis terniflora | yam-leaved virgin's-bower | Ranunculaceae | CT MA NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Clematis virginiana | Virginia virgin's-bower | Ranunculaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Clematis vitalba | white virgin's-bower | Ranunculaceae | ME | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Clethra alnifolia | coastal sweet-pepperbush | Clethraceae | CT MA ME NH RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Clinopodium acinos | basil-thyme | Lamiaceae | CT MA ME VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Clinopodium vulgare | wild basil | Lamiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Clintonia borealis | yellow blue-bead lily | Liliaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Coeloglossum viride | long-bracted green orchid | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Colchicum autumnale | autumn-crocus | Colchicaceae | MA NH VT | No | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Coleataenia longifolia | long-leaved redtop-panicgrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Collinsia parviflora | small-flowered blue-eyed Mary | Plantaginaceae | MA VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Collinsonia canadensis | northern horsebalm | Lamiaceae | CT MA NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Collomia linearis | narrow-leaved mountain-trumpet | Polemoniaceae | CT MA ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Colutea arborescens | bladder-senna | Fabaceae | CT MA RI | No | Woody Plants | Broad-leaved woody plants | |
| Comandra umbellata | bastard-toadflax | Comandraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Comarum palustre | marsh-cinquefoil, purple marsh-locks | Rosaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Commelina communis | Asiatic dayflower | Commelinaceae | CT MA ME NH RI VT | No | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Commelina diffusa | climbing dayflower | Commelinaceae | VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Comptonia peregrina | sweet-fern | Myricaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Conioselinum chinense | Chinese hemlock-parsley | Apiaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Conium maculatum | poison-hemlock | Apiaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Conopholis americana | American squaw-root | Orobanchaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Conringia orientalis | hare's-ear-mustard | Brassicaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Consolida ajacis | doubtful knight's-spur | Ranunculaceae | CT MA RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Consolida orientalis | Oriental knight's-spur | Ranunculaceae | VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Consolida regalis | royal knight's-spur | Ranunculaceae | CT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Convallaria majalis | European lily-of-the-valley | Ruscaceae | CT MA ME NH RI VT | No | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Convolvulus arvensis | field bindweed | Convolvulaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Coptidium lapponicum | Lapland-crowfoot | Ranunculaceae | ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Coptis trifolia | three-leaved goldthread | Ranunculaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Corallorhiza maculata | spotted coral-root | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Corallorhiza odontorhiza | fall coral-root | Orchidaceae | CT MA ME NH RI VT | Orchids and related plants | Orchids | ||
| Corallorhiza trifida | early coral-root | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Corema conradii | broom-crowberry | Ericaceae | MA ME | Yes | Woody Plants | Broad-leaved woody plants | |
| Coreopsis basalis | golden mane tickseed | Asteraceae | CT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Coreopsis grandiflora | large-flowered tickseed | Asteraceae | CT ME RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Coreopsis lanceolata | lance-leaved tickseed | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Coreopsis major | greater tickseed | Asteraceae | MA | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Coreopsis palmata | stiff tickseed | Asteraceae | MA | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Coreopsis pubescens | hairy tickseed | Asteraceae | CT MA | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Coreopsis rosea | pink tickseed | Asteraceae | MA RI | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Coreopsis tinctoria | golden tickseed | Asteraceae | CT MA ME RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Coreopsis tripteris | tall tickseed | Asteraceae | CT MA | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Coreopsis verticillata | thread-leaved tickseed | Asteraceae | CT MA | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Coriandrum sativum | coriander | Apiaceae | CT MA ME RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Coronilla scorpioides | yellow false crown-vetch | Fabaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Corrigiola litoralis | strapwort | Caryophyllaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Corydalis aurea | golden corydalis | Papaveraceae | MA NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Corydalis flavula | short-spurred corydalis | Papaveraceae | CT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Corydalis solida | spring corydalis | Papaveraceae | CT MA VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Corylus americana | American hazelnut | Betulaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Corylus cornuta | beaked hazelnut | Betulaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Corynephorus canescens | gray club-awn grass | Poaceae | CT MA ME | Grass-like plants | True grasses | ||
| Cosmos bipinnatus | garden cosmos | Asteraceae | CT MA ME NH RI | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Cosmos parviflorus | southwestern cosmos | Asteraceae | MA ME RI | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Cosmos sulphureus | sulphur cosmos | Asteraceae | CT MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Cota tinctoria | golden-chamomile | Asteraceae | CT MA ME NH RI VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Cotinus coggygria | European smoketree | Anacardiaceae | CT MA NH VT | No | Woody Plants | Broad-leaved woody plants | |
| Cotoneaster divaricatus | spreading cotoneaster | Rosaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Cotula coronopifolia | common brassbuttons | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Crassula aquatica | pygmy-weed | Crassulaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Crataegus asperifolia | rough-leaved hawthorn | Rosaceae | VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus bicknellii | Bicknell's hawthorn | Rosaceae | MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus biltmoreana | Biltmore hawthorn | Rosaceae | CT MA VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus boyntonii | stinking hawthorn | Rosaceae | CT MA VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus brainerdii | Brainerd's hawthorn | Rosaceae | MA VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus chrysocarpa | fireberry hawthorn | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus coccinea | scarlet hawthorn | Rosaceae | Yes | Woody Plants | Broad-leaved woody plants | ||
| Crataegus coccinioides | Kansas hawthorn | Rosaceae | CT MA VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus crus-galli | cockspur hawthorn | Rosaceae | CT MA ME RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus cyclophylla | round-leaved hawthorn | Rosaceae | VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus dissona | northern hawthorn | Rosaceae | CT MA NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus dodgei | Dodge's hawthorn | Rosaceae | CT MA VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus egglestonii | Eggleston's hawthorn | Rosaceae | VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus faxonii | Faxon's hawthorn | Rosaceae | ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus flabellata | Gray's hawthorn | Rosaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus flavida | yellow hawthorn | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus fluviatilis | river hawthorn | Rosaceae | MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus forbesae | Forbes' hawthorn | Rosaceae | CT MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus fretalis | Long Island Sound hawthorn | Rosaceae | CT MA ME | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus handyae | Handy's hawthorn | Rosaceae | CT MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus holmesiana | Holmes' hawthorn | Rosaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus ideae | Ide's hawthorn | Rosaceae | VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus intricata | entangled hawthorn | Rosaceae | CT MA NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus irrasa | zigzag hawthorn | Rosaceae | ME VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus jesupii | Jesup's hawthorn | Rosaceae | CT VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus jonesiae | Miss Jones' hawthorn | Rosaceae | ME | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus keepii | Keep's hawthorn | Rosaceae | MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus kennedyi | Kennedy's hawthorn | Rosaceae | VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus laurentiana | Brunet's hawthorn | Rosaceae | ME | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus levis | smooth hawthorn | Rosaceae | CT RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus lucorum | grove hawthorn | Rosaceae | VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus lumaria | thorny hawthorn | Rosaceae | CT MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus macracantha | long-thorned hawthorn | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus macrosperma | large-seeded hawthorn | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus monogyna | one-seeded hawthorn | Rosaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Crataegus oakesiana | Oakes' hawthorn | Rosaceae | ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus phaenopyrum | Washington hawthorn | Rosaceae | MA ME RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus pisifera | pea hawthorn | Rosaceae | VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus populnea | poplar hawthorn | Rosaceae | CT MA NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus pringlei | Pringle's hawthorn | Rosaceae | MA NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus pruinosa | frosted hawthorn | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus punctata | dotted hawthorn | Rosaceae | CT MA NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus scabrida | scabrous hawthorn | Rosaceae | NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus schizophylla | cleft-leaved hawthorn | Rosaceae | MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus schuettei | royal hawthorn | Rosaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus stonei | Stone's hawthorn | Rosaceae | MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus submollis | Quebec hawthorn | Rosaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus succulenta | fleshy hawthorn | Rosaceae | MA VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crataegus umbratilis | shaded hawthorn | Rosaceae | CT | Yes | Woody Plants | Broad-leaved woody plants | |
| Crepis biennis | rough hawk's-beard | Asteraceae | VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Crepis capillaris | smooth hawk's-beard | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Crepis foetida | stinking hawk's-beard | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Crepis nicaeensis | Turkish hawk's-beard | Asteraceae | MA VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Crepis setosa | bristly hawk's-beard | Asteraceae | CT VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Crepis tectorum | narrow-leaved hawk's-beard | Asteraceae | CT MA ME RI VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Crepis vesicaria | beaked hawk's-beard | Asteraceae | CT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Crocanthemum bicknellii | hoary frostweed | Cistaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Crocanthemum canadense | Canada frostweed | Cistaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Crocanthemum dumosum | bushy frostweed | Cistaceae | CT MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Crocanthemum propinquum | low frostweed | Cistaceae | CT MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Crocus vernus | Dutch crocus | Iridaceae | CT MA | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Crotalaria sagittalis | arrow-head rattlebox | Fabaceae | CT MA RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Croton capitatus | woolly croton | Euphorbiaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Crotonopsis elliptica | elliptic-leaved rushfoil | Euphorbiaceae | CT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Croton texensis | Texas croton | Euphorbiaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Crupina vulgaris | common crupina | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Crypsis schoenoides | swamp pricklegrass | Poaceae | MA VT | No | Grass-like plants | True grasses | |
| Cryptantha ambigua | basin cat's-eye | Boraginaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cryptogramma stelleri | slender rock-brake | Pteridaceae | CT MA ME NH VT | Yes | Ferns | True ferns and moonworts | |
| Cryptotaenia canadensis | Canada honewort | Apiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cucumis anguria | West India gherkin | Cucurbitaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cucumis melo | cantaloupe | Cucurbitaceae | CT MA NH RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cucumis myriocarpus | paddy melon | Cucurbitaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cucumis sativus | cucumber | Cucurbitaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cucurbita maxima | winter squash | Cucurbitaceae | MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cucurbita pepo | pumpkin | Cucurbitaceae | CT MA NH VT | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cuminum cyminum | cumin | Apiaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cuphea procumbens | creeping waxweed | Lythraceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Cuphea viscosissima | clammy waxweed | Lythraceae | CT MA RI | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Cuscuta approximata | alfalfa dodder | Convolvulaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cuscuta campestris | field dodder | Convolvulaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cuscuta cephalanthi | buttonbush dodder | Convolvulaceae | CT MA NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cuscuta compacta | compact dodder | Convolvulaceae | CT MA NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cuscuta coryli | hazel dodder | Convolvulaceae | CT MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cuscuta epithymum | clover dodder | Convolvulaceae | CT MA ME RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cuscuta europaea | greater dodder | Convolvulaceae | ME | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cuscuta gronovii | common dodder | Convolvulaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cuscuta indecora | collared dodder | Convolvulaceae | CT MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cuscuta pentagona | bush-clover dodder | Convolvulaceae | CT MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cuscuta polygonorum | smartweed dodder | Convolvulaceae | CT MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cyclachaena xanthiifolia | carelessweed | Asteraceae | CT MA ME NH RI VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Cycloloma atriplicifolium | winged-pigweed | Amaranthaceae | CT MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cydonia oblonga | quince | Rosaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Cymbalaria muralis | Kenilworth-ivy | Plantaginaceae | CT MA VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Cynanchum louiseae | black swallowwort | Apocynaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Cynanchum rossicum | pale swallowwort | Apocynaceae | CT MA ME NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Cynodon dactylon | Bermuda grass | Poaceae | CT MA | No | Grass-like plants | True grasses | |
| Cynoglossum amabile | Chinese hound's-tongue | Boraginaceae | MA NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cynoglossum microglochin | small-bristled hound's-tongue | Boraginaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cynoglossum officinale | common hound's-tongue | Boraginaceae | CT MA NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cynoglossum virginianum | wild hound's-tongue | Boraginaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Cynosurus cristatus | crested dogtail grass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Cyperus acuminatus | taper-tipped flatsedge | Cyperaceae | NH | Yes | Grass-like plants | All other grass-like plants | |
| Cyperus bipartitus | shining flatsedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Cyperus dentatus | toothed flatsedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Cyperus diandrus | umbrella flatsedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Cyperus echinatus | globe flatsedge | Cyperaceae | CT MA RI | Yes | Grass-like plants | All other grass-like plants | |
| Cyperus erythrorhizos | red-root flatsedge | Cyperaceae | CT MA ME NH RI | Yes | Grass-like plants | All other grass-like plants | |
| Cyperus esculentus | nut flatsedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Cyperus filicinus | fern flatsedge | Cyperaceae | CT MA ME NH RI | Yes | Grass-like plants | All other grass-like plants | |
| Cyperus flavescens | yellow flatsedge | Cyperaceae | MA | Yes | Grass-like plants | All other grass-like plants | |
| Cyperus fuscus | brown flatsedge | Cyperaceae | CT MA | No | Grass-like plants | All other grass-like plants | |
| Cyperus grayi | Gray's flatsedge | Cyperaceae | CT MA NH RI | Yes | Grass-like plants | All other grass-like plants | |
| Cyperus houghtonii | Houghton's flatsedge | Cyperaceae | MA ME NH VT | Yes | Grass-like plants | All other grass-like plants | |
| Cyperus iria | rice-field flatsedge | Cyperaceae | CT | No | Grass-like plants | All other grass-like plants | |
| Cyperus lupulinus | Great Plains flatsedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Cyperus microiria | lesser rice-field flatsedge | Cyperaceae | CT MA | No | Grass-like plants | All other grass-like plants | |
| Cyperus odoratus | rusty flatsedge | Cyperaceae | CT MA NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Cyperus polystachyos | many-spiked flatsedge | Cyperaceae | MA ME | Yes | Grass-like plants | All other grass-like plants | |
| Cyperus pseudovegetus | marsh flatsedge | Cyperaceae | MA | Yes | Grass-like plants | All other grass-like plants | |
| Cyperus retrorsus | pine barren flatsedge | Cyperaceae | MA | Yes | Grass-like plants | All other grass-like plants | |
| Cyperus schweinitzii | Schweinitz's flatsedge | Cyperaceae | MA | Yes | Grass-like plants | All other grass-like plants | |
| Cyperus squarrosus | awned flatsedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Cyperus strigosus | straw-colored flatsedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Cypripedium acaule | pink lady's-slipper | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Cypripedium arietinum | ram's-head lady's-slipper | Orchidaceae | CT MA ME NH VT | Yes | Orchids and related plants | Orchids | |
| Cypripedium parviflorum | yellow lady's-slipper | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Cypripedium reginae | showy lady's-slipper | Orchidaceae | CT MA ME NH VT | Yes | Orchids and related plants | Orchids | |
| Cystopteris bulbifera | bulblet fragile fern | Woodsiaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Cystopteris fragilis | fragile fern | Woodsiaceae | CT MA ME NH VT | Yes | Ferns | True ferns and moonworts | |
| Cystopteris laurentiana | Laurentian fragile fern | Woodsiaceae | CT MA VT | Yes | Ferns | True ferns and moonworts | |
| Cystopteris protrusa | southern fragile fern | Woodsiaceae | CT | Yes | Ferns | True ferns and moonworts | |
| Cystopteris tenuis | Mackay's fragile fern | Woodsiaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Cytisus scoparius | Scotch broom | Fabaceae | CT MA ME NH RI | No | Woody Plants | Broad-leaved woody plants | |
| Dactylis glomerata | orchard grass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Dactyloctenium aegyptium | Durban crowfoot grass | Poaceae | MA ME | No | Grass-like plants | True grasses | |
| Dactyloctenium radulans | button grass | Poaceae | MA | No | Grass-like plants | True grasses | |
| Dalea candida | white prairie-clover | Fabaceae | NH | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Dalea leporina | fox-tail prairie-clover | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Danthonia californica | California oatgrass | Poaceae | MA | Yes | Grass-like plants | True grasses | |
| Danthonia compressa | flattened oatgrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Danthonia spicata | poverty grass, poverty oatgrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Daphne cneorum | rose daphne | Thymelaeaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Daphne mezereum | February daphne, paradise plant | Thymelaeaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Dasiphora floribunda | shrubby-cinquefoil | Rosaceae | Yes | Woody Plants | Broad-leaved woody plants | ||
| Datura inoxia | downy thorn-apple | Solanaceae | CT MA ME NH RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Datura stramonium | jimsonweed, thorn-apple | Solanaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Datura wrightii | sacred thorn-apple | Solanaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Daucus carota | wild carrot | Apiaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Decodon verticillatus | swamp-loosestrife | Lythraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants; Woody Plants | Other herbaceous, flowering plants with opposite, whorled or no leaves; Broad-leaved woody plants | |
| Deinandra fasciculata | clustered moonshine-daisy | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Delphinium exaltatum | tall larkspur | Ranunculaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Dendrolycopodium dendroideum | prickly tree-clubmoss | Lycopodiaceae | CT MA ME NH RI VT | Yes | Ferns | Clubmosses and relatives, plus quillworts | |
| Dendrolycopodium hickeyi | Hickey's tree-clubmoss | Lycopodiaceae | CT MA ME NH RI VT | Yes | Ferns | Clubmosses and relatives, plus quillworts | |
| Dendrolycopodium obscurum | flat-branched tree-clubmoss | Lycopodiaceae | CT MA ME NH RI VT | Yes | Ferns | Clubmosses and relatives, plus quillworts | |
| Dennstaedtia punctilobula | eastern hay-scented fern | Dennstaedtiaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Deparia acrostichoides | silvery false spleenwort | Woodsiaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Deschampsia anadyrensis | glaucous hair grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Deschampsia cespitosa | tufted hair grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Deschampsia danthonioides | annual hair grass | Poaceae | ME | Yes | Grass-like plants | True grasses | |
| Deschampsia elongata | slender hair grass | Poaceae | ME | Yes | Grass-like plants | True grasses | |
| Deschampsia flexuosa | wavy hair grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Descurainia incana | mountain tansy-mustard | Brassicaceae | CT MA ME VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Descurainia pinnata | western tansy-mustard | Brassicaceae | MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Descurainia sophia | fine-leaved tansy-mustard | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Desmazeria rigida | fern grass | Poaceae | MA RI | No | Grass-like plants | True grasses | |
| Desmodium canadense | showy tick-trefoil | Fabaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Desmodium canescens | hoary tick-trefoil | Fabaceae | CT MA RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Desmodium ciliare | hairy small-leaved tick-trefoil | Fabaceae | CT MA RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Desmodium cuspidatum | large-bracted tick-trefoil | Fabaceae | CT MA NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Desmodium glabellum | smooth tick-trefoil | Fabaceae | CT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Desmodium marilandicum | smooth small-leaved tick-trefoil | Fabaceae | CT MA NH RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Desmodium obtusum | stiff tick-trefoil | Fabaceae | CT MA NH RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Desmodium paniculatum | panicled tick-trefoil | Fabaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Desmodium perplexum | perplexed tick-trefoil | Fabaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Desmodium rotundifolium | round-leaved trailing tick-trefoil | Fabaceae | CT MA NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Desmodium sessilifolium | sessile-leaved tick-trefoil | Fabaceae | CT MA RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Deutzia scabra | fuzzy pride-of-Rochester | Hydrangeaceae | CT MA RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Dianthus armeria | Deptford pink | Caryophyllaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Dianthus barbatus | sweet William pink | Caryophyllaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Dianthus carthusianorum | cluster-headed pink | Caryophyllaceae | NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Dianthus deltoides | maiden pink | Caryophyllaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Dianthus plumarius | garden pink | Caryophyllaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Diapensia lapponica | cushion-plant, pincushion-plant | Diapensiaceae | ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Dicentra canadensis | squirrel-corn | Papaveraceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Dicentra cucullaria | Dutchman's-breeches | Papaveraceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Dicentra eximia | wild bleeding-heart | Papaveraceae | MA RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Dicentra formosa | westerm bleeding-heart | Papaveraceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Dichanthelium acuminatum | hairy rosette-panicgrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Dichanthelium boreale | northern rosette-panicgrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Dichanthelium boscii | Bosc's rosette-panicgrass | Poaceae | CT RI | Yes | Grass-like plants | True grasses | |
| Dichanthelium clandestinum | deer-tongue rosette-panicgrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Dichanthelium commutatum | Ashe's variable rosette-panicgrass | Poaceae | CT MA RI | Yes | Grass-like plants | True grasses | |
| Dichanthelium depauperatum | starved rosette-panicgrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Dichanthelium dichotomum | forked rosette-panicgrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Dichanthelium latifolium | broad-leaved rosette-panicgrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Dichanthelium linearifolium | linear-leaved rosette-panicgrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Dichanthelium oligosanthes | few-flowered rosette-panicgrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Dichanthelium ovale | stiff-leaved rosette-panicgrass | Poaceae | CT MA RI | Yes | Grass-like plants | True grasses | |
| Dichanthelium scabriusculum | tall swamp rosette-panicgrass | Poaceae | CT MA RI | Yes | Grass-like plants | True grasses | |
| Dichanthelium scoparium | velvety rosette-panicgrass | Poaceae | CT MA RI | Yes | Grass-like plants | True grasses | |
| Dichanthelium sphaerocarpon | round-fruited rosette-panicgrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Dichanthelium wrightianum | Wright's rosette-panicgrass | Poaceae | MA RI | Yes | Grass-like plants | True grasses | |
| Dichanthelium xanthophysum | pale-leaved rosette-panicgrass | Poaceae | CT MA ME NH VT | Yes | Grass-like plants | True grasses | |
| Dictamnus albus | gasplant | Rutaceae | VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Diervilla lonicera | bush-honeysuckle | Caprifoliaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Digitalis grandiflora | yellow foxglove | Plantaginaceae | CT ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Digitalis lanata | Grecian foxglove | Plantaginaceae | CT MA NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Digitalis lutea | straw foxglove | Plantaginaceae | CT NH | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Digitalis purpurea | purple foxglove | Plantaginaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Digitaria cognata | fall crabgrass | Poaceae | CT MA NH RI VT | Yes | Grass-like plants | True grasses | |
| Digitaria filiformis | slender crabgrass | Poaceae | CT MA NH RI VT | Yes | Grass-like plants | True grasses | |
| Digitaria ischaemum | smooth crabgrass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Digitaria sanguinalis | hairy crabgrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Digitaria violascens | violet crabgrass | Poaceae | MA | No | Grass-like plants | True grasses | |
| Diodia teres | rough buttonweed | Rubiaceae | CT MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Diodia virginiana | Virginia buttonweed | Rubiaceae | CT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Dioscorea polystachya | Chinese yam | Dioscoreaceae | CT MA VT | No | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Dioscorea villosa | wild yam | Dioscoreaceae | CT MA RI | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Diospyros virginiana | common persimmon | Ebenaceae | CT MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Diphasiastrum complanatum | northern ground-cedar | Lycopodiaceae | ME NH VT | Yes | Ferns | Clubmosses and relatives, plus quillworts | |
| Diphasiastrum digitatum | southern ground-cedar | Lycopodiaceae | CT MA ME NH RI VT | Yes | Ferns | Clubmosses and relatives, plus quillworts | |
| Diphasiastrum sitchense | Sitka ground-cedar | Lycopodiaceae | ME NH | Yes | Ferns | Clubmosses and relatives, plus quillworts | |
| Diphasiastrum tristachyum | blue ground-cedar | Lycopodiaceae | CT MA ME NH RI VT | Yes | Ferns | Clubmosses and relatives, plus quillworts | |
| Diplazium pycnocarpon | narrow-leaved glade fern | Woodsiaceae | CT MA NH VT | Yes | Ferns | True ferns and moonworts | |
| Diplotaxis muralis | annual wall-rocket | Brassicaceae | CT MA ME | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Diplotaxis tenuifolia | perennial wall-rocket | Brassicaceae | CT MA ME | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Dipsacus fullonum | fuller's teasel | Caprifoliaceae | CT MA NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Dipsacus laciniatus | cut-leaved teasel | Caprifoliaceae | MA VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Dirca palustris | eastern leatherwood | Thymelaeaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Distichlis spicata | saltgrass | Poaceae | CT MA ME NH RI | Yes | Grass-like plants | True grasses | |
| Dittrichia graveolens | stinkwort | Asteraceae | CT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Doellingeria infirma | Appalachian white-aster | Asteraceae | CT MA RI | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Doellingeria umbellata | tall white-aster | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Doronicum pardalianches | greater false leopard's bane | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Draba arabisans | rock whitlow-mustard | Brassicaceae | ME VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Draba cana | canescent whitlow-mustard | Brassicaceae | ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Draba glabella | smooth whitlow-mustard | Brassicaceae | ME VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Draba reptans | Carolina whitlow-mustard | Brassicaceae | CT MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Draba verna | spring draba, spring whitlow-mustard | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Dracocephalum moldavica | Moldavian dragonhead | Lamiaceae | CT VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Dracocephalum parviflorum | American dragonhead | Lamiaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Dracocephalum thymiflorum | thyme-leaved dragonhead | Lamiaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Drosera anglica | English sundew | Droseraceae | ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Drosera filiformis | thread-leaved sundew | Droseraceae | CT MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Drosera intermedia | spatulate-leaved sundew | Droseraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Drosera linearis | slender-leaved sundew | Droseraceae | ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Drosera rotundifolia | round-leaved sundew | Droseraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Drymocallis arguta | tall wood-beauty | Rosaceae | CT MA ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Dryopteris campyloptera | mountain wood fern | Dryopteridaceae | CT MA ME NH VT | Yes | Ferns | True ferns and moonworts | |
| Dryopteris carthusiana | spinulose wood fern | Dryopteridaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Dryopteris clintoniana | Clinton's wood fern | Dryopteridaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Dryopteris cristata | crested wood fern | Dryopteridaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Dryopteris filix-mas | male wood fern | Dryopteridaceae | ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Dryopteris fragrans | fragrant wood fern | Dryopteridaceae | ME NH VT | Yes | Ferns | True ferns and moonworts | |
| Dryopteris goldiana | Goldie's wood fern | Dryopteridaceae | CT MA ME NH VT | Yes | Ferns | True ferns and moonworts | |
| Dryopteris intermedia | evergreen wood fern | Dryopteridaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Dryopteris marginalis | marginal wood fern | Dryopteridaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Dulichium arundinaceum | three-way sedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Dysphania ambrosioides | Mexican-tea | Amaranthaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Dysphania anthelmintica | wormseed | Amaranthaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Dysphania botrys | Jerusalem-oak | Amaranthaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Dysphania cristata | crested glandular-goosefoot | Amaranthaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Dysphania graveolens | fetid glandular-goosefoot | Amaranthaceae | MA ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Dysphania multifida | cut-leaved glandular-goosefoot | Amaranthaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Dysphania pumilio | clammy glandular-goosefoot | Amaranthaceae | CT MA RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Dyssodia papposa | fetid-marigold | Asteraceae | MA ME VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Echinacea pallida | pale purple coneflower | Asteraceae | CT MA ME | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Echinacea purpurea | eastern purple coneflower | Asteraceae | CT MA NH VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Echinochloa colona | awnless barnyard grass | Poaceae | MA VT | No | Grass-like plants | True grasses | |
| Echinochloa crus-galli | common barnyard grass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Echinochloa frumentacea | billion-dollar barnyard grass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Echinochloa muricata | American barnyard grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Echinochloa walteri | coast barnyard grass | Poaceae | CT MA NH RI | Yes | Grass-like plants | True grasses | |
| Echinocystis lobata | wild cucumber | Cucurbitaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Echinops sphaerocephalus | greater globe-thistle | Asteraceae | CT MA ME NH VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Echium creticum | Cretan viper's-bugloss | Boraginaceae | MA ME | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Echium plantagineum | plantain viper's-bugloss | Boraginaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Echium pustulatum | pustulose viper's-bugloss | Boraginaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Echium vulgare | common viper's-bugloss | Boraginaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Eclipta prostrata | false daisy | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Egeria densa | Brazilian-waterweed | Hydrocharitaceae | CT MA NH VT | No | Aquatic plants | Water plants with leaves and stems | |
| Eichhornia crassipes | common water-hyacinth | Pontederiaceae | CT | All other flowering non-woody plants; Orchids and related plants | Other herbaceous, flowering plants with alternate leaves; Irises, lilies, and other "monocots" | ||
| Elaeagnus angustifolia | Russian-olive | Elaeagnaceae | CT MA RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Elaeagnus pungens | thorny-olive | Elaeagnaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Elaeagnus umbellata | autumn-olive | Elaeagnaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Elatine americana | American waterwort | Elatinaceae | CT MA ME NH RI VT | Yes | Aquatic plants; All other flowering non-woody plants | Water plants with leaves and stems; Other herbaceous, flowering plants with alternate leaves | |
| Elatine minima | small waterwort | Elatinaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants; Aquatic plants | Other herbaceous, flowering plants with alternate leaves; Water plants with leaves and stems | |
| Elatine triandra | Eurasian waterwort | Elatinaceae | MA ME | Yes | Aquatic plants; All other flowering non-woody plants | Water plants with leaves and stems; Other herbaceous, flowering plants with alternate leaves | |
| Eleocharis acicularis | needle spikesedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants; Aquatic plants | All other grass-like plants; Water plants with leaves and stems | |
| Eleocharis aestuum | tidal spikesedge | Cyperaceae | CT ME VT | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis ambigens | ambiguous spikesedge | Cyperaceae | MA RI | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis compressa | flat-stemmed spikesedge | Cyperaceae | VT | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis diandra | Wright's spikesedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis elliptica | elliptic spikesedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis engelmannii | Engelmann's spikesedge | Cyperaceae | CT MA ME RI | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis equisetoides | horsetail spikesedge | Cyperaceae | CT MA RI | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis erythropoda | red-footed spikesedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis fallax | creeping spikesedge | Cyperaceae | MA | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis flavescens | yellow spikesedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis intermedia | mudflat spikesedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis melanocarpa | black-fruited spikesedge | Cyperaceae | MA RI | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis microcarpa | small-fruited spikesedge | Cyperaceae | CT MA | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis nitida | quill spikesedge | Cyperaceae | ME NH VT | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis obtusa | blunt spikesedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis ovata | ovoid spikesedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis palustris | common spikesedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis parvula | little-headed spikesedge | Cyperaceae | CT MA ME NH RI | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis quadrangulata | square-stemmed spikesedge | Cyperaceae | CT MA | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis quinqueflora | few-flowered spikesedge | Cyperaceae | MA ME NH VT | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis robbinsii | Robbins' spikesedge | Cyperaceae | CT MA ME NH RI VT | Yes | Aquatic plants; Grass-like plants | Water plants with leaves and stems; All other grass-like plants | |
| Eleocharis rostellata | beaked spikesedge | Cyperaceae | CT MA ME RI | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis tenuis | slender spikesedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis tricostata | three-angled spikesedge | Cyperaceae | MA RI | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis tuberculosa | long-tubercled spikesedge | Cyperaceae | CT MA ME NH RI | Yes | Grass-like plants | All other grass-like plants | |
| Eleocharis uniglumis | one-glumed spikesedge | Cyperaceae | CT MA ME NH RI | Yes | Grass-like plants | All other grass-like plants | |
| Eleusine indica | goosegrass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Eleutherococcus pentaphyllus | five-leaved-aralia | Apiaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Ellisia nyctelea | Aunt Lucy | Boraginaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Elodea canadensis | common waterweed | Hydrocharitaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Elodea nuttallii | free-flowered waterweed | Hydrocharitaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Elsholtzia ciliata | crested late-summer-mint | Lamiaceae | CT MA ME VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Elymus canadensis | Great Plains wild-rye | Poaceae | CT MA ME NH VT | Yes | Grass-like plants | True grasses | |
| Elymus curvatus | awnless wild-rye | Poaceae | MA RI | Yes | Grass-like plants | True grasses | |
| Elymus glabriflorus | southeastern wild-rye | Poaceae | CT MA RI | Yes | Grass-like plants | True grasses | |
| Elymus hystrix | eastern bottle-brush grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Elymus macgregorii | early wild-rye | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Elymus repens | creeping wild-rye | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Elymus riparius | eastern riverbank wild-rye | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Elymus trachycaulus | wheatgrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Elymus villosus | downy wild-rye | Poaceae | CT MA RI VT | Yes | Grass-like plants | True grasses | |
| Elymus virginicus | common eastern wild-rye | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Elymus wiegandii | Wiegand's wild-rye | Poaceae | CT MA ME NH VT | Yes | Grass-like plants | True grasses | |
| Emex spinosa | spiny threecorner-Jack | Polygonaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Empetrum atropurpureum | red crowberry | Ericaceae | ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Empetrum nigrum | black crowberry | Ericaceae | ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Endodeca serpentaria | Virginia serpentaria | Aristolochiaceae | CT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Epifagus virginiana | beech-drops | Orobanchaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Epigaea repens | trailing-arbutus | Ericaceae | CT MA ME NH RI VT | Yes | Woody Plants; All other flowering non-woody plants | Broad-leaved woody plants; Other herbaceous, flowering plants with alternate leaves | |
| Epilobium anagallidifolium | pimpernel willow-herb | Onagraceae | ME NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Epilobium ciliatum | fringed willow-herb | Onagraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Epilobium coloratum | eastern willow-herb | Onagraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Epilobium hirsutum | hairy willow-herb | Onagraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Epilobium hornemannii | Hornemann's willow-herb | Onagraceae | ME NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Epilobium lactiflorum | white-flowered willow-herb | Onagraceae | ME NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Epilobium leptophyllum | bog willow-herb | Onagraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Epilobium palustre | marsh willow-herb | Onagraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Epilobium parviflorum | small-flowered willow-herb | Onagraceae | VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Epilobium strictum | downy willow-herb | Onagraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Epipactis atrorubens | dark red helleborine | Orchidaceae | VT | No | Orchids and related plants | Orchids | |
| Epipactis helleborine | broad-leaved helleborine | Orchidaceae | CT MA ME NH RI VT | No | Orchids and related plants | Orchids | |
| Equisetum arvense | field horsetail | Equisetaceae | CT MA ME NH RI VT | Yes | Ferns | Horsetails and scouring-rushes | |
| Equisetum fluviatile | river horsetail | Equisetaceae | CT MA ME NH RI VT | Yes | Ferns | Horsetails and scouring-rushes | |
| Equisetum hyemale | tall scouring-rush | Equisetaceae | CT MA ME NH RI VT | Yes | Ferns | Horsetails and scouring-rushes | |
| Equisetum palustre | marsh horsetail | Equisetaceae | CT MA ME NH VT | Yes | Ferns | Horsetails and scouring-rushes | |
| Equisetum pratense | meadow horsetail | Equisetaceae | CT MA ME NH VT | Yes | Ferns | Horsetails and scouring-rushes | |
| Equisetum scirpoides | dwarf scouring-rush | Equisetaceae | CT MA ME NH VT | Yes | Ferns | Horsetails and scouring-rushes | |
| Equisetum sylvaticum | wood horsetail | Equisetaceae | CT MA ME NH RI VT | Yes | Ferns | Horsetails and scouring-rushes | |
| Equisetum variegatum | variegated scouring-rush | Equisetaceae | CT MA ME NH RI VT | Yes | Ferns | Horsetails and scouring-rushes | |
| Eragrostis capillaris | lace lovegrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Eragrostis cilianensis | stinking lovegrass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Eragrostis curvula | weeping lovegrass | Poaceae | MA RI | No | Grass-like plants | True grasses | |
| Eragrostis frankii | sandbar lovegrass | Poaceae | CT MA ME VT | Yes | Grass-like plants | True grasses | |
| Eragrostis hypnoides | teel lovegrass | Poaceae | CT MA ME NH VT | Yes | Grass-like plants | True grasses | |
| Eragrostis intermedia | plains lovegrass | Poaceae | MA ME | Yes | Grass-like plants | True grasses | |
| Eragrostis mexicana | Mexican lovegrass | Poaceae | CT MA ME | Yes | Grass-like plants | True grasses | |
| Eragrostis minor | little lovegrass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Eragrostis pectinacea | tufted lovegrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Eragrostis pilosa | India lovegrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Eragrostis spectabilis | purple lovegrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Erechtites hieraciifolius | American burnweed | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Eremochloa ophiuroides | centipede grass | Poaceae | MA | No | Grass-like plants | True grasses | |
| Erica cinerea | Scotch heath | Ericaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Erica tetralix | cross-leaved heath | Ericaceae | CT MA ME NH | No | Woody Plants | Broad-leaved woody plants | |
| Erica vagans | Cornish heath | Ericaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Erigeron acris | bitter fleabane | Asteraceae | ME | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Erigeron annuus | annual fleabane | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Erigeron canadensis | Canada fleabane | Asteraceae | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Erigeron hyssopifolius | hyssop-leaved fleabane | Asteraceae | ME VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Erigeron philadelphicus | Philadelphia fleabane | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Erigeron pulchellus | Robin's plantain fleabane | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Erigeron strigosus | rough fleabane | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Eriocaulon aquaticum | seven-angled pipewort | Eriocaulaceae | CT MA ME NH RI VT | Yes | Orchids and related plants; Aquatic plants | Irises, lilies, and other "monocots"; Water plants with leaves and stems | |
| Eriocaulon parkeri | Parker's pipewort | Eriocaulaceae | CT MA ME | Yes | Orchids and related plants; Aquatic plants | Irises, lilies, and other "monocots"; Water plants with leaves and stems | |
| Eriophorum angustifolium | tall cottongrass, tall cottonsedge | Cyperaceae | ME NH | Yes | Grass-like plants | All other grass-like plants | |
| Eriophorum gracile | slender cottongrass, slender cottonsedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Eriophorum tenellum | few-nerved cottongrass, few-nerved cottonsedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Eriophorum vaginatum | tussock cottongrass, tussock cottonsedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Eriophorum virginicum | tawny cottongrass, tawny cottonsedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Eriophorum viridicarinatum | green-keeled cottongrass, green-keeled cottonsedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Erodium botrys | long-beaked stork's-bill | Geraniaceae | MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Erodium ciconium | common stork's-bill | Geraniaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Erodium cicutarium | red-stemmed stork's-bill | Geraniaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Erodium cygnorum | Australian stork's-bill | Geraniaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Erodium malacoides | Mediterranean stork's-bill | Geraniaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Erodium moschatum | musky stork's-bill | Geraniaceae | CT MA ME | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Erodium stephanianum | Stephen's stork's-bill | Geraniaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Erucastrum gallicum | common dog-mustard | Brassicaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Eruca vesicaria | garden-rocket | Brassicaceae | CT MA VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Eryngium amethystinum | amethyst eryngo | Apiaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Eryngium planum | plains eryngo | Apiaceae | CT MA VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Eryngium yuccifolium | button eryngo | Apiaceae | CT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Erysimum capitatum | sand-dune wallflower | Brassicaceae | ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Erysimum cheiranthoides | wormseed wallflower | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Erysimum hieraciifolium | European wallflower | Brassicaceae | MA VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Erysimum inconspicuum | shy wallflower | Brassicaceae | MA ME NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Erysimum odoratum | fragrant wallflower | Brassicaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Erysimum repandum | spreading wallflower | Brassicaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Erythronium albidum | white trout-lily | Liliaceae | CT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Erythronium americanum | Amerian trout-lily | Liliaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Eschscholzia californica | California-poppy | Papaveraceae | CT MA NH | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Eubotrys racemosa | swamp deciduous dog-laurel, swamp dog-hobble | Ericaceae | CT MA RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Euchiton involucratus | common creeping-cudweed | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Euclidium syriacum | Syrian-mustard | Brassicaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Eudianthe coeli-rosa | rose catchfly | Caryophyllaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Euonymus alatus | burning-bush, winged spindle-tree | Celastraceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Euonymus atropurpureus | eastern spindle-tree | Celastraceae | CT MA ME NH RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Euonymus europaeus | European spindle-tree | Celastraceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Euonymus fortunei | climbing spindle-tree | Celastraceae | CT MA ME RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Euonymus phellomanus | cork spindle-tree | Celastraceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Eupatorium album | white thoroughwort | Asteraceae | CT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Eupatorium altissimum | tall thoroughwort | Asteraceae | CT MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Eupatorium hyssopifolium | hyssop-leaved boneset, hyssop-leaved thoroughwort | Asteraceae | CT MA RI | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Eupatorium novae-angliae | New England thoroughwort | Asteraceae | MA RI | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Eupatorium perfoliatum | boneset thoroughwort | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Eupatorium pilosum | ragged thoroughwort | Asteraceae | CT MA RI | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Eupatorium pubescens | hairy boneset, hairy thoroughwort | Asteraceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Eupatorium rotundifolium | round-leaved thoroughwort | Asteraceae | CT MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Eupatorium serotinum | late thoroughwort | Asteraceae | CT MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Eupatorium sessilifolium | upland boneset, upland thoroughwort | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Eupatorium torreyanum | Torrey's thoroughwort | Asteraceae | CT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Euphorbia corollata | flowering spurge | Euphorbiaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Euphorbia cyparissias | cypress spurge | Euphorbiaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Euphorbia dentata | toothed spurge | Euphorbiaceae | CT MA NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Euphorbia esula | leafy spurge | Euphorbiaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Euphorbia glyptosperma | rib-seeded sandmat | Euphorbiaceae | MA ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Euphorbia helioscopia | sun spurge | Euphorbiaceae | CT MA ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Euphorbia ipecacuanhae | ipecac spurge | Euphorbiaceae | CT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Euphorbia lathyris | gopher spurge | Euphorbiaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Euphorbia maculata | spotted sandmat | Euphorbiaceae | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Euphorbia marginata | mountain snow spurge | Euphorbiaceae | CT MA NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Euphorbia nutans | eyebane sandmat | Euphorbiaceae | CT MA NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Euphorbia peplus | petty spurge | Euphorbiaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Euphorbia platyphyllos | broad-leaved spurge | Euphorbiaceae | MA VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Euphorbia polygonifolia | seaside sandmat | Euphorbiaceae | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Euphorbia prostrata | prostrate sandmat | Euphorbiaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Euphorbia serpens | matted sandmat | Euphorbiaceae | NH | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Euphorbia serpyllifolia | thyme-leaved sandmat | Euphorbiaceae | NH | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Euphorbia vermiculata | hairy sandmat | Euphorbiaceae | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Euphorbia virgata | slender leafy spurge | Euphorbiaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Euphrasia micrantha | northern eyebright | Orobanchaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Euphrasia nemorosa | common eyebright | Orobanchaceae | MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Euphrasia oakesii | Oakes' eyebright | Orobanchaceae | ME NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Euphrasia randii | Rand's eyebright | Orobanchaceae | ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Euphrasia stricta | strict eyebright | Orobanchaceae | MA ME RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Euphrasia suborbicularis | round-leaved eyebright | Orobanchaceae | ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Euphrasia tetraquetra | seacliff eyebright | Orobanchaceae | ME | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Eurybia divaricata | white wood-aster | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Eurybia macrophylla | large-leaved wood-aster | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Eurybia radula | rough wood-aster | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Eurybia schreberi | Schreber's wood-aster | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Eurybia spectabilis | purple wood-aster | Asteraceae | CT MA RI | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Euthamia caroliniana | coastal plain grass-leaved-goldenrod, slender goldentop | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Euthamia graminifolia | common grass-leaved-goldenrod, flat-top goldentop | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Eutrochium dubium | coastal plain Joe-Pye weed | Asteraceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Eutrochium fistulosum | hollow Joe-Pye weed | Asteraceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Eutrochium maculatum | spotted Joe-Pye weed | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Eutrochium purpureum | purple Joe-Pye weed | Asteraceae | CT MA NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Exochorda racemosa | common pearlbrush | Rosaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Fagopyrum esculentum | garden buckwheat | Polygonaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Fagopyrum tataricum | green buckwheat | Polygonaceae | MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Fagus grandifolia | American beech | Fagaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Fagus sylvatica | European beech | Fagaceae | CT MA ME RI | No | Woody Plants | Broad-leaved woody plants | |
| Falcaria vulgaris | sickleweed | Apiaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Fallopia baldschuanica | Chinese bindweed | Polygonaceae | CT MA | No | All other flowering non-woody plants; Woody Plants | Other herbaceous, flowering plants with alternate leaves; Broad-leaved woody plants | |
| Fallopia cilinodis | fringed bindweed | Polygonaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Fallopia convolvulus | black bindweed | Polygonaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Fallopia cristata | crested bindweed | Polygonaceae | CT MA RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Fallopia dumetorum | thicket bindweed | Polygonaceae | CT MA RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Fallopia japonica | Japanese knotweed | Polygonaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Fallopia sachalinensis | giant knotweed | Polygonaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Fallopia scandens | climbing bindweed | Polygonaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Fatoua villosa | hairy crabweed | Moraceae | CT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Festuca brachyphylla | alpine fescue | Poaceae | VT | Yes | Grass-like plants | True grasses | |
| Festuca filiformis | fine-leaved sheep fescue | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Festuca ovina | sheep fescue | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Festuca prolifera | proliferous fescue | Poaceae | ME NH | Yes | Grass-like plants | True grasses | |
| Festuca rubra | red fescue | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Festuca subverticillata | nodding fescue | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Festuca trachyphylla | hard fescue | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Ficaria verna | fig-crowfoot, lesser celandine | Ranunculaceae | CT MA NH RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ficus carica | common fig | Moraceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Filago vulgaris | common cotton-rose | Asteraceae | MA | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Filipendula rubra | prairie dropwort, queen-of-the-prairie | Rosaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Filipendula ulmaria | meadow dropwort | Rosaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Filipendula vulgaris | common dropwort | Rosaceae | CT ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Fimbristylis autumnalis | slender fimbry | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Flaveria trinervia | clustered yellowtops | Asteraceae | MA | Yes and no (some introduced) | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Floerkea proserpinacoides | false mermaidweed | Limnanthaceae | CT MA VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Foeniculum vulgare | sweet fennel | Apiaceae | CT MA RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Forsythia suspensa | weeping forsythia | Oleaceae | CT MA VT | No | Woody Plants | Broad-leaved woody plants | |
| Forsythia viridissima | green-stemmed forsythia | Oleaceae | CT MA NH | No | Woody Plants | Broad-leaved woody plants | |
| Fragaria vesca | woodland strawberry | Rosaceae | CT MA ME NH RI VT | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Fragaria virginiana | common strawberry | Rosaceae | CT MA ME NH RI VT | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Frangula alnus | glossy false buckthorn | Rhamnaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Frankenia pulverulenta | European sea-heath | Frankeniaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Frasera albicaulis | white-stemmed elkweed | Gentianaceae | MA | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Fraxinus americana | white ash | Oleaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Fraxinus excelsior | European ash | Oleaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Fraxinus nigra | black ash | Oleaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Fraxinus pennsylvanica | green ash | Oleaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Froelichia gracilis | slender cotton-weed | Amaranthaceae | CT MA NH RI VT | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Fuirena pumila | dwarf umbrella-sedge | Cyperaceae | CT MA RI | Yes | Grass-like plants | All other grass-like plants | |
| Fuirena squarrosa | hairy umbrella-sedge | Cyperaceae | MA | Yes | Grass-like plants | All other grass-like plants | |
| Fumaria officinalis | common fumitory | Papaveraceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Gadellia lactiflora | milky-bellflower | Campanulaceae | NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Gagea fragifera | star-of-Bethlehem | Liliaceae | VT | No | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Gaillardia aristata | common blanket-flower | Asteraceae | CT MA NH | Yes and no (some introduced) | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Gaillardia pulchella | rosering blanket-flower | Asteraceae | CT MA ME NH VT | Yes and no (some introduced) | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Galanthus nivalis | snowdrop | Amaryllidaceae | MA | No | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Galax urceolata | beetleweed | Diapensiaceae | MA NH | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galearis spectabilis | showy orchid | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Galega officinalis | professor-weed | Fabaceae | CT MA ME | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Galeopsis bifida | split-lipped hemp-nettle | Lamiaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galeopsis ladanum | red hemp-nettle | Lamiaceae | CT MA ME RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galeopsis tetrahit | brittle-stemmed hemp-nettle | Lamiaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galinsoga parviflora | gallant soldier, lesser quickweed | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Galinsoga quadriradiata | common quickweed, shaggy soldier | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Galium album | white bedstraw | Rubiaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galium aparine | scratch bedstraw | Rubiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galium asprellum | rough bedstraw | Rubiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galium boreale | northern bedstraw | Rubiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galium brevipes | limestone swamp bedstraw | Rubiaceae | MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galium circaezans | forest licorice bedstraw | Rubiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galium divaricatum | Lamarck's bedstraw | Rubiaceae | VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galium glaucum | waxy bedstraw | Rubiaceae | CT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galium kamtschaticum | boreal bedstraw | Rubiaceae | ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galium labradoricum | northern bog bedstraw | Rubiaceae | MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galium lanceolatum | lance-leaved licorice bedstraw | Rubiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galium mollugo | whorled bedstraw | Rubiaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galium obtusum | blunt-leaved bedstraw | Rubiaceae | CT MA NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galium odoratum | sweet-scented bedstraw, sweet woodruff | Rubiaceae | MA RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galium palustre | marsh bedstraw | Rubiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galium pilosum | hairy bedstraw | Rubiaceae | CT MA NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galium sylvaticum | wood bedstraw | Rubiaceae | CT MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galium tinctorium | stiff three-petaled bedstraw | Rubiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galium tricornutum | rough-fruited bedstraw | Rubiaceae | RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galium trifidum | three-petaled bedstraw | Rubiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galium triflorum | fragrant bedstraw | Rubiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Galium verum | yellow bedstraw | Rubiaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Gamochaeta pensylvanica | Pennsylvania cudweed | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Gamochaeta purpurea | purple cudweed | Asteraceae | CT MA ME RI | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Gastridium phleoides | nit grass | Poaceae | MA | No | Grass-like plants | True grasses | |
| Gaultheria hispidula | creeping spicy-wintergreen | Ericaceae | CT MA ME NH RI VT | Yes | Woody Plants; All other flowering non-woody plants | Broad-leaved woody plants; Other herbaceous, flowering plants with alternate leaves | |
| Gaultheria procumbens | eastern spicy-wintergreen, wintergreen | Ericaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants; Woody Plants | Other herbaceous, flowering plants with alternate leaves; Broad-leaved woody plants | |
| Gaylussacia baccata | black huckleberry | Ericaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Gaylussacia bigeloviana | dwarf huckleberry | Ericaceae | CT MA ME NH RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Gaylussacia frondosa | blue huckleberry | Ericaceae | CT MA NH RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Genista tinctoria | dyer's greenweed | Fabaceae | CT MA ME RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Gentiana andrewsii | Andrew's bottle gentian | Gentianaceae | CT MA VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Gentiana clausa | closed gentian, meadow bottle gentian | Gentianaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Gentiana linearis | narrow-leaved gentian | Gentianaceae | MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Gentiana rubricaulis | red-stemmed gentian | Gentianaceae | ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Gentianella amarella | northern dwarf-gentian | Gentianaceae | ME VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Gentianella quinquefolia | stiff dwarf-gentian | Gentianaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Gentianopsis crinita | greater fringed-gentian | Gentianaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Geocaulon lividum | false toadflax | Comandraceae | ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Geranium aequale | smooth Dove's-foot crane's-bill | Geraniaceae | MA VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Geranium bicknellii | northern crane's-bill | Geraniaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Geranium carolinianum | Carolina crane's-bill | Geraniaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Geranium columbinum | long-stalked crane's-bill | Geraniaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Geranium dissectum | cut-leaved crane's-bill | Geraniaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Geranium maculatum | spotted crane's-bill | Geraniaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Geranium molle | dove's-foot crane's-bill | Geraniaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Geranium pratense | meadow crane's-bill | Geraniaceae | CT MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Geranium pusillum | small-flowered crane's-bill | Geraniaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Geranium pyrenaicum | hedgerow crane's-bill | Geraniaceae | VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Geranium robertianum | herb-Robert, mountain crane's-bill | Geraniaceae | CT MA ME NH RI VT | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Geranium sanguineum | bloody crane's-bill | Geraniaceae | MA ME RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Geranium sibiricum | Siberian crane's-bill | Geraniaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Geranium thunbergii | dew-drop crane's-bill | Geraniaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Geum aleppicum | yellow avens | Rosaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Geum canadense | white avens | Rosaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Geum fragarioides | Appalachian barren-strawberry | Rosaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Geum laciniatum | floodplain avens | Rosaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Geum macrophyllum | large-leaved avens | Rosaceae | ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Geum peckii | White Mountain avens | Rosaceae | NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Geum rivale | water avens | Rosaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Geum urbanum | town avens | Rosaceae | MA RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Geum vernum | spring avens | Rosaceae | MA VT | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Geum virginianum | cream-colored avens | Rosaceae | CT MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Gilia achilleifolia | blue gilia | Polemoniaceae | MA ME | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Gilia interior | inland gilia | Polemoniaceae | MA | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Gilia tricolor | bird's-eye gilia | Polemoniaceae | MA | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Gillenia trifoliata | Bowman's-root | Rosaceae | MA | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Glandularia canadensis | rose mock-vervain | Verbenaceae | CT | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Glaucium flavum | yellow horn-poppy | Papaveraceae | CT MA RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Glebionis carinata | tricolor daisy | Asteraceae | MA | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Glebionis coronaria | crown daisy | Asteraceae | MA ME VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Glebionis segetum | corn daisy | Asteraceae | CT MA ME | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Glechoma hederacea | Gill-over-the-ground | Lamiaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Gleditsia triacanthos | honey-locust | Fabaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Glossostigma cleistanthum | mud-mat | Phrymaceae | CT MA RI | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Glyceria acutiflora | sharp-scaled manna grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants; Aquatic plants | True grasses; Water plants with leaves and stems | |
| Glyceria borealis | northern manna grass | Poaceae | CT MA ME NH VT | Yes | Aquatic plants; Grass-like plants | Water plants with leaves and stems; True grasses | |
| Glyceria canadensis | rattlesnake manna grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Glyceria fluitans | water manna grass | Poaceae | MA | No | Aquatic plants; Grass-like plants | Water plants with leaves and stems; True grasses | |
| Glyceria grandis | American manna grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Glyceria laxa | flaccid manna grass | Poaceae | CT MA ME NH VT | Yes | Grass-like plants | True grasses | |
| Glyceria maxima | reed manna grass | Poaceae | CT MA | No | Grass-like plants | True grasses | |
| Glyceria melicaria | northeastern manna grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Glyceria obtusa | Atlantic manna grass | Poaceae | CT MA ME NH RI | Yes | Grass-like plants | True grasses | |
| Glyceria septentrionalis | floating manna grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants; Aquatic plants | True grasses; Water plants with leaves and stems | |
| Glyceria striata | fowl manna grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Glycine max | soybean | Fabaceae | MA VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Glycyrrhiza lepidota | American licorice | Fabaceae | CT MA ME RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Gnaphalium uliginosum | brown cudweed | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Gomphrena globosa | common globe-amaranth | Amaranthaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Goodyera oblongifolia | giant rattlesnake-plantain | Orchidaceae | ME VT | Yes | Orchids and related plants | Orchids | |
| Goodyera pubescens | downy rattlesnake-plantain | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Goodyera repens | dwarf rattlesnake-plantain | Orchidaceae | CT MA ME NH VT | Yes | Orchids and related plants | Orchids | |
| Goodyera tesselata | checkered rattlesnake-plantain | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Gossypium hirsutum | upland cotton | Malvaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Graphephorum melicoides | graphephorum | Poaceae | ME NH VT | Yes | Grass-like plants | True grasses | |
| Gratiola lutea | golden hedge-hyssop | Plantaginaceae | CT MA ME NH RI VT | Yes | Aquatic plants; All other flowering non-woody plants | Water plants with leaves and stems; Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Gratiola neglecta | clammy hedge-hyssop | Plantaginaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Gratiola virginiana | round-fruited hedge-hyssop | Plantaginaceae | RI | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Grindelia hirsutula | hairy gum-weed | Asteraceae | CT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Grindelia squarrosa | curly-top gum-weed | Asteraceae | CT MA ME NH RI VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Guizotia abyssinica | niger-seed | Asteraceae | CT MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Gymnadenia conopsea | fragrant orchid | Orchidaceae | CT | No | Orchids and related plants | Orchids | |
| Gymnocarpium dryopteris | northern oak fern | Woodsiaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Gymnocarpium jessoense | Nahanni oak fern | Woodsiaceae | VT | Yes | Ferns | True ferns and moonworts | |
| Gymnocladus dioicus | Kentucky coffee-tree | Fabaceae | CT MA ME | Yes | Woody Plants | Broad-leaved woody plants | |
| Gypsophila elegans | showy baby's-breath | Caryophyllaceae | CT MA ME NH RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Gypsophila muralis | low baby's-breath | Caryophyllaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Gypsophila paniculata | tall baby's-breath | Caryophyllaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Gypsophila scorzonerifolia | glandular baby's-breath | Caryophyllaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Hackelia deflexa | nodding stickseed | Boraginaceae | ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Hackelia virginiana | Virginia stickseed | Boraginaceae | CT MA NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Halenia deflexa | American spurred-gentian | Gentianaceae | MA ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Halesia carolina | Carolina silverbell | Styracaceae | CT MA RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Hamamelis virginiana | American witch-hazel | Hamamelidaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Harrimanella hypnoides | moss-plant | Ericaceae | ME NH | Woody Plants; All other flowering non-woody plants | Broad-leaved woody plants; Other herbaceous, flowering plants with alternate leaves | ||
| Hedeoma hispida | rough false pennyroyal | Lamiaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Hedeoma pulegioides | American false pennyroyal | Lamiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Hedera helix | English-ivy | Apiaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Hedysarum alpinum | alpine sweet-vetch | Fabaceae | ME VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Helanthium tenellum | dwarf burhead | Alismataceae | CT MA | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Helenium amarum | narrow-leaved sneezeweed | Asteraceae | CT MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Helenium autumnale | fall sneezeweed | Asteraceae | CT MA ME RI VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Helenium flexuosum | purple-headed sneezeweed | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Helianthus annuus | common sunflower | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Helianthus debilis | cucumber-leaved sunflower | Asteraceae | CT MA ME NH RI VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Helianthus decapetalus | thin-leaved sunflower | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Helianthus divaricatus | woodland sunflower | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Helianthus giganteus | tall sunflower | Asteraceae | CT MA ME VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Helianthus grosseserratus | saw-toothed sunflower | Asteraceae | CT MA ME NH | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Helianthus hirsutus | hairy sunflower | Asteraceae | CT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Helianthus maximiliani | Maximilian's sunflower | Asteraceae | CT MA ME | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Helianthus microcephalus | small-headed sunflower | Asteraceae | CT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Helianthus mollis | ashy sunflower | Asteraceae | CT MA ME RI | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Helianthus occidentalis | naked-stemmed sunflower | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Helianthus pauciflorus | stiff sunflower | Asteraceae | CT MA ME NH RI | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Helianthus petiolaris | prairie sunflower | Asteraceae | CT MA ME RI VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Helianthus strumosus | pale-leaved sunflower | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Helianthus tuberosus | tuberous sunflower | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Heliomeris multiflora | showy false goldeneye | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Heliopsis helianthoides | sunflower-everlasting | Asteraceae | CT MA ME NH VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Heliotropium amplexicaule | clasping heliotrope | Boraginaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Heliotropium curassavicum | seaside heliotrope | Boraginaceae | ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Heliotropium europaeum | European heliotrope | Boraginaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Heliotropium indicum | Indian heliotrope | Boraginaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Helminthotheca echioides | bristly ox-tongue | Asteraceae | CT MA ME VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Hemerocallis fulva | orange day-lily | Hemerocallidaceae | CT MA ME NH RI VT | No | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Hemerocallis lilioasphodelus | yellow day-lily | Hemerocallidaceae | CT MA ME RI VT | No | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Heracleum mantegazzianum | giant cow-parsnip | Apiaceae | CT MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Heracleum maximum | American cow-parsnip | Apiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Heracleum sphondylium | European cow-parsnip | Apiaceae | CT MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Herniaria glabra | smooth rupturewort | Caryophyllaceae | ME | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Herniaria hirsuta | hairy rupturewort | Caryophyllaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Hesperis matronalis | dame's-rocket | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Heteranthera dubia | grass-leaved mud-plantain | Pontederiaceae | CT MA ME NH VT | Yes | Aquatic plants; Orchids and related plants | Water plants with leaves and stems; Irises, lilies, and other "monocots" | |
| Heteranthera reniformis | kidney-leaved mud-plantain | Pontederiaceae | CT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Heterosperma pinnatum | wingpetal | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Heterotheca subaxillaris | camphor false golden-aster | Asteraceae | CT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Heuchera americana | common alum-root | Saxifragaceae | CT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Hibiscus moscheutos | swamp rose-mallow | Malvaceae | CT MA NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Hibiscus syriacus | shrubby rose-mallow | Malvaceae | CT | No | Woody Plants | Broad-leaved woody plants | |
| Hibiscus trionum | Venice rose-mallow | Malvaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Hieracium aurantiacum | orange hawkweed | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Hieracium caespitosum | yellow hawkweed | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Hieracium flagellare | whip hawkweed | Asteraceae | CT MA ME NH VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Hieracium gronovii | beaked hawkweed | Asteraceae | CT MA RI | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Hieracium kalmii | Canada hawkweed | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Hieracium lachenalii | common hawkweed | Asteraceae | CT MA ME | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Hieracium maculatum | spotted hawkweed | Asteraceae | ME VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Hieracium murorum | wall hawkweed | Asteraceae | CT MA ME NH VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Hieracium paniculatum | panicled hawkweed | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Hieracium pilosella | mouse-ear hawkweed | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Hieracium piloselloides | glaucous hawkweed | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Hieracium praealtum | tall hawkweed | Asteraceae | CT MA ME NH VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Hieracium robinsonii | Robinson's hawkweed | Asteraceae | ME NH | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Hieracium sabaudum | Savoy hawkweed | Asteraceae | CT MA ME VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Hieracium scabrum | rough hawkweed | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Hieracium umbellatum | narrow-leaved hawkweed | Asteraceae | NH VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Hieracium venosum | rattlesnake hawkweed | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Hippuris vulgaris | common mare's-tail | Plantaginaceae | MA ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Holcus lanatus | common velvet grass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Holcus mollis | creeping velvet grass | Poaceae | MA VT | No | Grass-like plants | True grasses | |
| Holosteum umbellatum | jagged-chickweed | Caryophyllaceae | CT MA RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Honckenya peploides | seaside-sandwort | Caryophyllaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Hordeum brachyantherum | meadow barley | Poaceae | MA NH | Yes | Grass-like plants | True grasses | |
| Hordeum jubatum | fox-tail barley | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Hordeum murinum | mouse barley | Poaceae | CT MA ME | No | Grass-like plants | True grasses | |
| Hordeum pusillum | little barley | Poaceae | CT MA ME NH | Yes | Grass-like plants | True grasses | |
| Hordeum vulgare | common barley | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Hosta lancifolia | narrow-leaved plantain-lily | Hostaceae | CT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Hosta ventricosa | blue plantain-lily | Hostaceae | CT MA NH RI VT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Hottonia inflata | American featherfoil | Primulaceae | CT MA ME NH RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Houstonia caerulea | little bluet | Rubiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Houstonia longifolia | long-leaved bluet | Rubiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Houstonia purpurea | large bluet | Rubiaceae | CT MA ME VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Hudsonia ericoides | pine-barren false heather | Cistaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Hudsonia tomentosa | sand false heather, woolly beach-heather | Cistaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Humulus japonicus | Japanese hop | Cannabaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Humulus lupulus | common hop, hops | Cannabaceae | CT MA ME NH RI VT | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Huperzia appressa | mountain firmoss | Huperziaceae | CT MA ME NH VT | Yes | Ferns | Clubmosses and relatives, plus quillworts | |
| Huperzia lucidula | shining firmoss | Huperziaceae | CT MA ME NH RI VT | Yes | Ferns | Clubmosses and relatives, plus quillworts | |
| Huperzia selago | northern firmoss | Huperziaceae | MA ME NH VT | Yes | Ferns | Clubmosses and relatives, plus quillworts | |
| Hybanthus concolor | green-violet | Violaceae | CT VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Hydrangea arborescens | American hydrangea | Hydrangeaceae | CT MA VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Hydrangea cinerea | ashy hydrangea | Hydrangeaceae | MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Hydrangea paniculata | panicled hydrangea | Hydrangeaceae | CT MA ME NH RI | No | Woody Plants | Broad-leaved woody plants | |
| Hydrangea quercifolia | oak-leaved hydrangea | Hydrangeaceae | CT | Yes | Woody Plants | Broad-leaved woody plants | |
| Hydrastis canadensis | goldenseal | Ranunculaceae | CT MA VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Hydrilla verticillata | water-thyme | Hydrocharitaceae | CT MA ME | No | Aquatic plants | Water plants with leaves and stems | |
| Hydrocharis morsus-ranae | European frog's-bit | Hydrocharitaceae | VT | No | Aquatic plants; Orchids and related plants | Water plants with leaves and stems; Irises, lilies, and other "monocots" | |
| Hydrocotyle americana | American marsh-pennywort | Apiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Hydrocotyle umbellata | many-flowered marsh-pennywort | Apiaceae | CT MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Hydrocotyle verticillata | whorled marsh-pennywort | Apiaceae | CT MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Hydrophyllum canadense | blunt-leaved waterleaf | Boraginaceae | MA VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Hydrophyllum virginianum | eastern waterleaf | Boraginaceae | CT MA NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Hylodesmum glutinosum | pointed-leaved tick-trefoil | Fabaceae | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Hylodesmum nudiflorum | naked tick-trefoil | Fabaceae | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Hylotelephium erythrostictum | garden orpine | Crassulaceae | MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Hylotelephium spectabile | showy orpine | Crassulaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Hylotelephium telephium | purple orpine, sedum | Crassulaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Hymenoxys odorata | poison rubberweed | Asteraceae | ME | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Hyoscyamus niger | black henbane | Solanaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Hypericum adpressum | creeping St. John's-wort | Hypericaceae | CT MA RI | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Hypericum ascyron | great St. John's-wort | Hypericaceae | CT MA ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Hypericum boreale | northern St. John's-wort | Hypericaceae | CT MA ME NH RI VT | Yes | Aquatic plants; All other flowering non-woody plants | Water plants with leaves and stems; Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Hypericum canadense | lesser St. John's-wort | Hypericaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Hypericum densiflorum | bushy St. John's-wort | Hypericaceae | MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Hypericum dolabriforme | straggling St. John's-wort | Hypericaceae | CT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Hypericum ellipticum | pale St. John's-wort | Hypericaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Hypericum frondosum | cedar glade St. John's-wort | Hypericaceae | CT MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Hypericum gentianoides | orange-grass St. John's-wort | Hypericaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Hypericum majus | greater Canada St. John's-wort | Hypericaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Hypericum mutilum | dwarf St. John's-wort | Hypericaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Hypericum perforatum | common St. John's-wort | Hypericaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Hypericum prolificum | shrubby St. John's-wort | Hypericaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Hypericum punctatum | spotted St. John's-wort | Hypericaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Hypericum stragulum | multi-stemmed St. John's-wort, St. Andrew's cross | Hypericaceae | MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Hypochaeris glabra | smooth cat's-ear | Asteraceae | MA ME | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Hypochaeris radicata | hairy cat's-ear | Asteraceae | CT MA ME NH RI VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Hypopitys lanuginosa | hairy pine-sap | Ericaceae | CT MA NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Hypopitys monotropa | yellow pine-sap | Ericaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Hypoxis hirsuta | common star-grass | Hypoxidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Hyssopus officinalis | hyssop | Lamiaceae | CT MA ME VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Iberis amara | rocket candytuft | Brassicaceae | CT MA ME | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Iberis sempervirens | edging candytuft | Brassicaceae | NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Iberis umbellata | globe candytuft | Brassicaceae | ME NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ilex aquifolium | English holly | Aquifoliaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Ilex crenata | Japanese holly | Aquifoliaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Ilex glabra | evergreen winterberry, inkberry | Aquifoliaceae | CT MA ME NH RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Ilex laevigata | smooth winterberry | Aquifoliaceae | CT MA ME NH RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Ilex montana | big-leaved holly | Aquifoliaceae | CT MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Ilex mucronata | mountain holly | Aquifoliaceae | Yes | Woody Plants | Broad-leaved woody plants | ||
| Ilex opaca | American holly | Aquifoliaceae | CT MA ME RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Ilex verticillata | common winterberry | Aquifoliaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Illecebrum verticillatum | coral necklace | Caryophyllaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Impatiens capensis | jewelweed, spotted touch-me-not | Balsaminaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Impatiens glandulifera | Himalaya touch-me-not, ornamental jewelweed | Balsaminaceae | CT MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Impatiens pallida | pale jewelweed, pale touch-me-not | Balsaminaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Inula helenium | horse yellowhead | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Inula salicina | willow-leaved yellowhead | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Ionactis linariifolia | flax-leaved stiff-aster | Asteraceae | CT MA ME NH RI VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Ipomoea coccinea | red morning-glory | Convolvulaceae | CT MA RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ipomoea hederacea | ivy-leaved morning-glory | Convolvulaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ipomoea hederifolia | scarlet morning-glory | Convolvulaceae | MA VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ipomoea lacunosa | white morning-glory | Convolvulaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ipomoea pandurata | wild sweet potato morning-glory | Convolvulaceae | CT MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ipomoea purpurea | common morning-glory | Convolvulaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ipomoea quamoclit | Cypress-vine morning-glory | Convolvulaceae | VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ipomoea tricolor | granny morning-glory | Convolvulaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ipomopsis rubra | standing-cypress skyrocket | Polemoniaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Iris cristata | crested iris | Iridaceae | MA | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Iris domestica | blackberry-lily | Iridaceae | CT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Iris ensata | Russian iris | Iridaceae | CT VT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Iris germanica | German iris | Iridaceae | CT MA ME | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Iris hookeri | beach-head iris | Iridaceae | ME | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Iris prismatica | slender blue iris | Iridaceae | CT MA ME NH RI | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Iris pseudacorus | yellow iris | Iridaceae | CT MA ME NH RI VT | No | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Iris pumila | dwarf iris | Iridaceae | ME | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Iris sibirica | Siberian iris | Iridaceae | CT MA NH VT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Iris tectorum | wall iris | Iridaceae | NH | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Iris versicolor | blue iris | Iridaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Isoetes acadiensis | Acadian quillwort | Isoetaceae | CT MA ME NH | Yes | Ferns; Aquatic plants | Clubmosses and relatives, plus quillworts; Water plants with leaves and stems | |
| Isoetes echinospora | spiny-spored quillwort | Isoetaceae | CT MA ME NH RI VT | Yes | Aquatic plants; Ferns | Water plants with leaves and stems; Clubmosses and relatives, plus quillworts | |
| Isoetes engelmannii | Engelmann's quillwort | Isoetaceae | CT MA ME NH RI VT | Yes | Aquatic plants; Ferns | Water plants with leaves and stems; Clubmosses and relatives, plus quillworts | |
| Isoetes hieroglyphica | carved quillwort | Isoetaceae | ME | Yes | Aquatic plants; Ferns | Water plants with leaves and stems; Clubmosses and relatives, plus quillworts | |
| Isoetes lacustris | lake quillwort | Isoetaceae | MA ME NH VT | Yes | Aquatic plants; Ferns | Water plants with leaves and stems; Clubmosses and relatives, plus quillworts | |
| Isoetes prototypus | prototype quillwort | Isoetaceae | ME | Yes | Ferns; Aquatic plants | Clubmosses and relatives, plus quillworts; Water plants with leaves and stems | |
| Isoetes riparia | Canada shore quillwort | Isoetaceae | CT MA ME NH RI VT | Yes | Aquatic plants; Ferns | Water plants with leaves and stems; Clubmosses and relatives, plus quillworts | |
| Isoetes tuckermanii | Tuckerman's quillwort | Isoetaceae | CT MA ME NH RI VT | Yes | Aquatic plants; Ferns | Water plants with leaves and stems; Clubmosses and relatives, plus quillworts | |
| Isotrema macrophyllum | large-leaved Dutchman's pipe | Aristolochiaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Isotrema tomentosum | woolly Dutchman's pipe | Aristolochiaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Isotria medeoloides | small whorled pogonia | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Isotria verticillata | large whorled pogonia | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Iva annua | rough marsh-elder | Asteraceae | MA ME | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Iva frutescens | maritime marsh-elder | Asteraceae | CT MA ME NH RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Jacobaea vulgaris | tansy ragwort | Asteraceae | MA ME | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Jasione montana | sheepbit | Campanulaceae | CT MA RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Juglans ailantifolia | Japanese walnut | Juglandaceae | MA RI | No | Woody Plants | Broad-leaved woody plants | |
| Juglans cinerea | butternut, white walnut | Juglandaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Juglans nigra | black walnut | Juglandaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Juncus acuminatus | sharp-fruited rush | Juncaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus alpinoarticulatus | northern green rush | Juncaceae | ME NH VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus ambiguus | seaside toad rush | Juncaceae | CT MA ME | Yes | Grass-like plants | All other grass-like plants | |
| Juncus anthelatus | Wiegand's rush | Juncaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus articulatus | joint-leaved rush | Juncaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus balticus | Baltic rush | Juncaceae | MA ME NH VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus biflorus | large grass-leaved rush | Juncaceae | MA | Yes | Grass-like plants | All other grass-like plants | |
| Juncus brachycarpus | white-root rush | Juncaceae | CT MA RI | Yes | Grass-like plants | All other grass-like plants | |
| Juncus brachycephalus | small-headed rush | Juncaceae | CT MA ME NH VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus brevicaudatus | short-tailed rush | Juncaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus bufonius | toad rush | Juncaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus canadensis | Canada rush | Juncaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus compressus | round-fruited rush | Juncaceae | ME VT | No | Grass-like plants | All other grass-like plants | |
| Juncus conglomeratus | bunch-flowered soft rush | Juncaceae | MA ME NH | Yes | Grass-like plants | All other grass-like plants | |
| Juncus debilis | weak rush | Juncaceae | CT MA RI | Yes | Grass-like plants | All other grass-like plants | |
| Juncus dichotomus | forked rush | Juncaceae | CT MA ME NH RI | Yes | Grass-like plants | All other grass-like plants | |
| Juncus diffusissimus | slim-fruited rush | Juncaceae | CT MA | Yes | Grass-like plants | All other grass-like plants | |
| Juncus dudleyi | Dudley's rush | Juncaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus effusus | common soft rush | Juncaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus ensifolius | sword-leaved rush | Juncaceae | RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus filiformis | thread rush | Juncaceae | MA ME NH VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus gerardii | saltmarsh rush | Juncaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus greenei | Greene's rush | Juncaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus inflexus | European meadow rush | Juncaceae | MA | No | Grass-like plants | All other grass-like plants | |
| Juncus marginatus | grass-leaved rush | Juncaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus militaris | bayonet rush | Juncaceae | CT MA ME NH RI VT | Yes | Aquatic plants; Grass-like plants | Water plants with leaves and stems; All other grass-like plants | |
| Juncus nodosus | knotted rush | Juncaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus pelocarpus | brown-fruited rush | Juncaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus pervetus | blunt-flower rush | Juncaceae | MA | Grass-like plants | All other grass-like plants | ||
| Juncus pylaei | Pylaei's soft rush | Juncaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus secundus | lopsided rush | Juncaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus stygius | moor rush | Juncaceae | ME NH | Yes | Grass-like plants | All other grass-like plants | |
| Juncus subcaudatus | somewhat-tailed rush | Juncaceae | CT VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus subtilis | greater creeping rush | Juncaceae | ME | Yes | Grass-like plants | All other grass-like plants | |
| Juncus tenuis | path rush | Juncaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus torreyi | Torrey's rush | Juncaceae | MA ME VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus trifidus | highland rush | Juncaceae | ME NH VT | Yes | Grass-like plants | All other grass-like plants | |
| Juncus vaseyi | Vasey's rush | Juncaceae | ME VT | Yes | Grass-like plants | All other grass-like plants | |
| Juniperus communis | common juniper | Cupressaceae | CT MA ME NH RI VT | Yes | Woody Plants | Needle-leaved woody plants | |
| Juniperus horizontalis | creeping juniper | Cupressaceae | MA ME NH VT | Yes | Woody Plants | Needle-leaved woody plants | |
| Juniperus virginiana | eastern red cedar | Cupressaceae | CT MA ME NH RI VT | Yes | Woody Plants | Needle-leaved woody plants | |
| Justicia americana | American water-willow | Acanthaceae | VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Kalmia angustifolia | sheep American-laurel, sheep-laurel | Ericaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Kalmia latifolia | mountain American-laurel, mountain laurel | Ericaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Kalmia polifolia | bog American-laurel, bog laurel | Ericaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Kalmia procumbens | Alpine-azalea | Ericaceae | ME NH | Yes | Woody Plants | Broad-leaved woody plants | |
| Kalopanax septemlobus | castor-aralia | Apiaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Kerria japonica | Japanese-rose | Rosaceae | CT NH RI | No | Woody Plants | Broad-leaved woody plants | |
| Kickxia elatine | sharp-leaved cancerwort | Plantaginaceae | CT MA ME RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Kickxia spuria | round-leaved cancerwort | Plantaginaceae | RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Knautia arvensis | bluebuttons, field scabiosa | Caprifoliaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Kochia scoparia | summer-cypress | Amaranthaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Koeleria macrantha | prairie Koeler's grass | Poaceae | ME VT | Yes | Grass-like plants | True grasses | |
| Koelreuteria paniculata | golden rain-tree | Sapindaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Kolkwitzia amabilis | beautybush | Caprifoliaceae | MA VT | No | Woody Plants | Broad-leaved woody plants | |
| Krigia biflora | two-flowered dwarf-dandelion | Asteraceae | CT ME | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Krigia virginica | Virginia dwarf-dandelion | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Kummerowia striata | Japanese-clover | Fabaceae | CT RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Kyllinga gracillima | pasture greenhead-sedge | Cyperaceae | CT | No | Grass-like plants | All other grass-like plants | |
| Laburnum anagyroides | golden chain-tree | Fabaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Lachnanthes caroliniana | Carolina bloodroot | Haemodoraceae | CT MA RI | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Lactuca biennis | tall blue lettuce | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Lactuca canadensis | tall lettuce | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Lactuca hirsuta | tall hairy lettuce | Asteraceae | CT MA ME NH RI VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Lactuca sativa | cultivated lettuce | Asteraceae | MA ME VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Lactuca serriola | prickly lettuce | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Lagenaria siceraria | bottle gourd, calabash | Cucurbitaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lamium album | white henbit | Lamiaceae | MA ME | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Lamium amplexicaule | common henbit, henbit deadnettle | Lamiaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Lamium galeobdolon | yellow henbit | Lamiaceae | MA ME VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Lamium maculatum | spotted henbit | Lamiaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Lamium purpureum | red henbit | Lamiaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Lamprocapnos spectabilis | common bleeding-heart | Papaveraceae | CT ME | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Landoltia punctata | spotted-duck-meal | Araceae | MA | Yes | Aquatic plants | Tiny water plants with no true stem | |
| Laportea canadensis | Canada wood-nettle | Urticaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lappula occidentalis | flat-spined sheepburr | Boraginaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lappula squarrosa | bristly sheepburr | Boraginaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lapsana communis | common nipplewort | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Larix decidua | European larch | Pinaceae | CT MA ME NH RI VT | No | Woody Plants | Needle-leaved woody plants | |
| Larix laricina | American larch | Pinaceae | CT MA ME NH RI VT | Yes | Woody Plants | Needle-leaved woody plants | |
| Lasthenia californica | California goldfields | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Lasthenia minor | coastal goldfields | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Lathyrus aphaca | yellow vetchling | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Lathyrus japonicus | beach vetchling | Fabaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lathyrus latifolius | everlasting vetchling | Fabaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lathyrus ochroleucus | cream vetchling | Fabaceae | VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Lathyrus odoratus | sweet vetchling | Fabaceae | CT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Lathyrus palustris | marsh vetchling | Fabaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lathyrus pratensis | meadow vetchling | Fabaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lathyrus sativus | white vetchling | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Lathyrus sylvestris | narrow-leaved vetchling | Fabaceae | CT MA NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Lathyrus tuberosus | tuber vetchling | Fabaceae | CT MA ME VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Lavandula angustifolia | English lavender | Lamiaceae | VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Lavatera trimestris | rose-mallow | Malvaceae | CT VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Layia platyglossa | coastal tidytips | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Lechea intermedia | round-fruited pinweed | Cistaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lechea maritima | beach pinweed | Cistaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lechea minor | thyme-leaved pinweed | Cistaceae | CT MA RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lechea mucronata | hairy pinweed | Cistaceae | CT MA NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lechea pulchella | Leggett's pinweed | Cistaceae | CT MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lechea tenuifolia | narrow-leaved pinweed | Cistaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Leersia oryzoides | rice cut grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Leersia virginica | white cut grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Lemna minor | common duckweed | Araceae | CT MA ME NH RI VT | Yes | Aquatic plants | Tiny water plants with no true stem | |
| Lemna minuta | least duckweed | Araceae | MA | Yes | Aquatic plants | Tiny water plants with no true stem | |
| Lemna perpusilla | minute duckweed | Araceae | MA VT | Yes | Aquatic plants | Tiny water plants with no true stem | |
| Lemna trisulca | ivy-leaved duckweed | Araceae | CT MA ME NH RI VT | Yes | Aquatic plants | Tiny water plants with no true stem | |
| Lemna turionifera | turion duckweed | Araceae | CT MA RI VT | Yes | Aquatic plants | Tiny water plants with no true stem | |
| Lemna valdiviana | pale duckweed | Araceae | CT MA NH RI | Yes | Aquatic plants | Tiny water plants with no true stem | |
| Lens culinaris | lentil | Fabaceae | CT MA ME | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Leontodon hispidus | bristly hawkbit | Asteraceae | CT RI | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Leontodon saxatilis | little hawkbit | Asteraceae | CT MA RI VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Leonurus cardiaca | motherwort | Lamiaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Lepidium campestre | field pepperweed | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lepidium densiflorum | prairie pepperweed | Brassicaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lepidium didymum | lesser swine-cress | Brassicaceae | CT MA ME NH RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lepidium draba | heart-podded pepperweed | Brassicaceae | CT MA ME RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lepidium heterophyllum | variable-leaved pepperweed | Brassicaceae | MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lepidium latifolium | broad-leaved pepperweed | Brassicaceae | CT MA NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lepidium perfoliatum | clasping pepperweed | Brassicaceae | CT MA ME | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lepidium ruderale | stinking pepperweed | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lepidium sativum | garden pepperweed | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lepidium squamatum | greater swine-cress | Brassicaceae | MA RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lepidium virginicum | poor-man's pepperweed | Brassicaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Leptochloa fusca | bearded sprangletop | Poaceae | CT MA NH RI VT | Yes | Grass-like plants | True grasses | |
| Leptochloa panicea | needle sprangletop | Poaceae | MA | Yes | Grass-like plants | True grasses | |
| Lespedeza angustifolia | narrow-leaved bush-clover | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Lespedeza bicolor | two-colored bush-clover | Fabaceae | CT MA VT | All other flowering non-woody plants; Woody Plants | Other herbaceous, flowering plants with alternate leaves; Broad-leaved woody plants | ||
| Lespedeza capitata | round-headed bush-clover | Fabaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lespedeza cuneata | Chinese bush-clover | Fabaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Lespedeza cyrtobotrya | leafy bush-clover | Fabaceae | CT MA | Woody Plants; All other flowering non-woody plants | Broad-leaved woody plants; Other herbaceous, flowering plants with alternate leaves | ||
| Lespedeza frutescens | violet bush-clover | Fabaceae | CT MA NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lespedeza hirta | hairy bush-clover | Fabaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lespedeza procumbens | trailing bush-clover | Fabaceae | CT MA NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lespedeza repens | creeping bush-clover | Fabaceae | CT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lespedeza stuevei | tall bush-clover | Fabaceae | CT MA RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Lespedeza thunbergii | Thunberg's bush-clover | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Lespedeza violacea | wand bush-clover | Fabaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lespedeza virginica | slender bush-clover | Fabaceae | CT MA NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Leucanthemella serotina | giant-daisy | Asteraceae | CT MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Leucanthemum vulgare | ox-eye daisy | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Leucojum aestivum | summer snowflake | Amaryllidaceae | CT MA ME | No | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Leucophysalis grandiflora | large false ground-cherry | Solanaceae | VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Leucothoe fontanesiana | fetterbush, highland dog-laurel | Ericaceae | MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Levisticum officinale | garden lovage | Apiaceae | CT MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Leymus mollis | American lyme grass | Poaceae | MA ME NH | Yes | Grass-like plants | True grasses | |
| Liatris novae-angliae | northern blazing star | Asteraceae | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Liatris pycnostachya | thick-spiked blazing star | Asteraceae | MA ME | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Liatris spicata | sessile-headed blazing star | Asteraceae | CT MA RI | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Ligusticum scoticum | Scotch wild lovage | Apiaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ligustrum obtusifolium | border privet | Oleaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Ligustrum ovalifolium | California privet | Oleaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Ligustrum sinense | Chinese privet | Oleaceae | CT MA RI | No | Woody Plants | Broad-leaved woody plants | |
| Ligustrum vulgare | European privet | Oleaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Lilaeopsis chinensis | eastern grasswort | Apiaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lilium canadense | Canada lily | Liliaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Lilium lancifolium | lance-leaved tiger lily | Liliaceae | CT MA ME NH RI VT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Lilium philadelphicum | wood lily | Liliaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Lilium superbum | Turk's-cap lily | Liliaceae | CT MA NH RI | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Limnobium spongiosa | American spongeplant | Hydrocharitaceae | CT | Yes | Aquatic plants; Orchids and related plants | Water plants with leaves and stems; Irises, lilies, and other "monocots" | |
| Limonium carolinianum | Carolina sea-lavender | Plumbaginaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Limosella australis | Atlantic mudwort | Scrophulariaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Linaria dalmatica | Dalmatian toadflax | Plantaginaceae | CT MA ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Linaria genistifolia | broom-leaved toadflax | Plantaginaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Linaria maroccana | Moroccan toadflax | Plantaginaceae | CT MA ME NH | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Linaria pinifolia | pine-needle toadflax | Plantaginaceae | CT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Linaria repens | striped toadflax | Plantaginaceae | MA ME | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Linaria spartea | ballast toadflax | Plantaginaceae | CT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Linaria vulgaris | butter-and-eggs toadflax | Plantaginaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lindera benzoin | northern spicebush | Lauraceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Lindernia dubia | yellow-seeded false pimpernel | Linderniaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Linnaea borealis | American twinflower | Caprifoliaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants; Woody Plants | Other herbaceous, flowering plants with opposite, whorled or no leaves; Broad-leaved woody plants | |
| Linum catharticum | white flax | Linaceae | MA ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Linum intercursum | sandplain yellow flax | Linaceae | CT MA RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Linum medium | common yellow flax | Linaceae | CT MA ME RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Linum perenne | blue flax | Linaceae | ME VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Linum radiola | all-seed flax | Linaceae | ME | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Linum striatum | ridged yellow flax | Linaceae | CT MA RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Linum sulcatum | grooved yellow flax | Linaceae | CT MA NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Linum usitatissimum | cultivated flax | Linaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Linum virginianum | woodland yellow flax | Linaceae | CT MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Liparis liliifolia | lily-leaved wide-lipped orchid | Orchidaceae | CT MA RI VT | Yes | Orchids and related plants | Orchids | |
| Liparis loeselii | Loesel's wide-lipped orchid | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Lipocarpha micrantha | small-flowered dwarf-bulrush | Cyperaceae | CT MA ME NH RI | Yes | Grass-like plants | All other grass-like plants | |
| Liquidambar styraciflua | sweet-gum | Altingiaceae | CT MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Liriodendron tulipifera | tuliptree | Magnoliaceae | CT MA RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Lithospermum officinale | European gromwell | Boraginaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Littorella americana | American shoreweed | Plantaginaceae | ME VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Lobelia cardinalis | cardinal-flower, red lobelia | Campanulaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lobelia dortmanna | water lobelia | Campanulaceae | CT MA ME NH RI VT | Yes | Aquatic plants; All other flowering non-woody plants | Water plants with leaves and stems; Other herbaceous, flowering plants with alternate leaves | |
| Lobelia inflata | bladder-pod lobelia, indian-tobacco | Campanulaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lobelia kalmii | brook lobelia | Campanulaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lobelia siphilitica | blue lobelia, great lobelia | Campanulaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lobelia spicata | pale-spiked lobelia | Campanulaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lobularia maritima | sweet-alyssum | Brassicaceae | CT MA ME RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Logfia minima | little false cotton-rose | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Lolium multiflorum | Italian rye grass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Lolium perenne | perennial rye grass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Lolium temulentum | darnel rye-grass, poison darnel | Poaceae | CT MA ME VT | No | Grass-like plants | True grasses | |
| Lomatogonium rotatum | marsh-felwort | Gentianaceae | ME | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Lonicera canadensis | American honeysuckle | Caprifoliaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Lonicera dioica | wild honeysuckle | Caprifoliaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Lonicera hirsuta | hairy honeysuckle | Caprifoliaceae | MA VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Lonicera japonica | Japanese honeysuckle | Caprifoliaceae | CT MA ME NH RI | No | Woody Plants | Broad-leaved woody plants | |
| Lonicera maackii | Amur honeysuckle | Caprifoliaceae | CT MA ME NH | No | Woody Plants | Broad-leaved woody plants | |
| Lonicera morrowii | Morrow's honeysuckle | Caprifoliaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Lonicera oblongifolia | swamp honeysuckle | Caprifoliaceae | ME VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Lonicera periclymenum | European honeysuckle | Caprifoliaceae | ME | No | Woody Plants | Broad-leaved woody plants | |
| Lonicera reticulata | grape honeysuckle | Caprifoliaceae | MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Lonicera sempervirens | trumpet honeysuckle | Caprifoliaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Lonicera tatarica | Tatarian honeysuckle | Caprifoliaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Lonicera villosa | mountain honeysuckle | Caprifoliaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Lonicera xylosteum | fly honeysuckle | Caprifoliaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Lotus corniculatus | garden bird's-foot-trefoil | Fabaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lotus unifoliatus | American bird's-foot-trefoil | Fabaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Ludwigia alternifolia | square-pod water-primrose | Onagraceae | CT MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ludwigia palustris | common water-primrose | Onagraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Ludwigia polycarpa | many-fruited water-primrose | Onagraceae | CT MA ME VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ludwigia sphaerocarpa | round-pod water-primrose | Onagraceae | CT MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lunaria annua | annual honesty | Brassicaceae | CT MA ME RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lupinus perennis | sundial lupine | Fabaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Lupinus polyphyllus | blue lupine | Fabaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Luzula acuminata | hairy wood rush | Juncaceae | CT MA ME NH VT | Yes | Grass-like plants | All other grass-like plants | |
| Luzula bulbosa | bulbous wood rush | Juncaceae | CT MA | Yes | Grass-like plants | All other grass-like plants | |
| Luzula campestris | field wood rush | Juncaceae | CT MA | No | Grass-like plants | All other grass-like plants | |
| Luzula confusa | northern wood rush | Juncaceae | ME NH | Yes | Grass-like plants | All other grass-like plants | |
| Luzula echinata | hedgehog wood rush | Juncaceae | CT MA | Yes | Grass-like plants | All other grass-like plants | |
| Luzula luzuloides | oak-forest wood rush | Juncaceae | CT MA ME VT | No | Grass-like plants | All other grass-like plants | |
| Luzula multiflora | common wood rush | Juncaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Luzula pallidula | pale European wood rush | Juncaceae | VT | No | Grass-like plants | All other grass-like plants | |
| Luzula parviflora | small-flowered wood rush | Juncaceae | MA ME NH VT | Yes | Grass-like plants | All other grass-like plants | |
| Luzula spicata | spiked wood rush | Juncaceae | ME NH VT | Yes | Grass-like plants | All other grass-like plants | |
| Lychnis chalcedonica | scarlet lychnis | Caryophyllaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Lychnis coronaria | mullein lychnis | Caryophyllaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Lychnis flos-cuculi | ragged robin lychnis | Caryophyllaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Lycium barbarum | matrimony-vine | Solanaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Lycium chinense | Chinese matrimony-vine | Solanaceae | CT MA ME NH VT | No | Woody Plants | Broad-leaved woody plants | |
| Lycopodiella alopecuroides | foxtail bog-clubmoss | Lycopodiaceae | CT MA ME RI | Yes | Ferns | Clubmosses and relatives, plus quillworts | |
| Lycopodiella appressa | appressed bog-clubmoss, southern bog-clubmoss | Lycopodiaceae | CT MA ME NH RI VT | Yes | Ferns | Clubmosses and relatives, plus quillworts | |
| Lycopodiella inundata | northern bog-clubmoss | Lycopodiaceae | CT MA ME NH RI VT | Yes | Ferns | Clubmosses and relatives, plus quillworts | |
| Lycopodium clavatum | common clubmoss, running clubmoss | Lycopodiaceae | CT MA ME NH RI VT | Yes | Ferns | Clubmosses and relatives, plus quillworts | |
| Lycopodium lagopus | one-cone clubmoss | Lycopodiaceae | CT MA ME NH RI VT | Yes | Ferns | Clubmosses and relatives, plus quillworts | |
| Lycopus americanus | American water-horehound | Lamiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Lycopus amplectens | clasping water-horehound | Lamiaceae | CT MA RI | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Lycopus asper | western water-horehound | Lamiaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Lycopus europaeus | European water-horehound | Lamiaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Lycopus rubellus | stalked water-horehound | Lamiaceae | CT MA RI | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Lycopus uniflorus | northern water-horehound | Lamiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Lycopus virginicus | Virginia water-horehound | Lamiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Lygodium palmatum | American climbing fern | Lygodiaceae | CT MA NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Lyonia ligustrina | maleberry | Ericaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Lyonia mariana | piedmont staggerbush | Ericaceae | CT RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Lysimachia arvensis | scarlet pimpernel | Myrsinaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Lysimachia borealis | starflower | Myrsinaceae | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Lysimachia ciliata | fringed yellow-loosestrife | Myrsinaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Lysimachia clethroides | goose-neck yellow-loosestrife | Myrsinaceae | CT MA ME | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Lysimachia hybrida | lowland yellow-loosestrife | Myrsinaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Lysimachia maritima | sea-milkwort | Myrsinaceae | MA ME NH RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lysimachia minima | chaffweed pimpernel | Myrsinaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Lysimachia nummularia | creeping yellow-loosestrife | Myrsinaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Lysimachia punctata | large yellow-loosestrife | Myrsinaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Lysimachia quadriflora | four-flowered yellow-loosestrife | Myrsinaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Lysimachia quadrifolia | whorled yellow-loosestrife | Myrsinaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Lysimachia terrestris | swamp yellow-loosestrife | Myrsinaceae | CT MA ME NH RI VT | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lysimachia thyrsiflora | tufted yellow-loosestrife | Myrsinaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lysimachia vulgaris | garden yellow-loosestrife | Myrsinaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Lythrum alatum | winged loosestrife | Lythraceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Lythrum hyssopifolia | hyssop-leaved loosestrife | Lythraceae | MA ME NH RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Lythrum junceum | rose loosestrife | Lythraceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Lythrum lineare | saltmarsh loosestrife | Lythraceae | CT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Lythrum salicaria | purple loosestrife | Lythraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Lythrum virgatum | European wand loosestrife | Lythraceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Macleaya cordata | plume-poppy | Papaveraceae | CT MA ME NH RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Maclura pomifera | Osage-orange | Moraceae | CT MA RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Madia glomerata | mountain tarplant | Asteraceae | CT ME VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Madia sativa | Chile tarplant | Asteraceae | CT MA VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Magnolia acuminata | cucumber-tree | Magnoliaceae | CT MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Magnolia tripetala | umbrella-tree | Magnoliaceae | CT MA RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Magnolia virginiana | sweet-bay | Magnoliaceae | CT MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Maianthemum canadense | Canada-mayflower | Ruscaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Maianthemum racemosum | feathery false Solomon's-seal | Ruscaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Maianthemum stellatum | star-like false Solomon's-seal | Ruscaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Maianthemum trifolium | three-leaved false Solomon's-seal | Ruscaceae | CT MA ME NH RI VT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Malaxis bayardii | Bayard's adder's-mouth | Orchidaceae | CT MA RI | Yes | Orchids and related plants | Orchids | |
| Malaxis monophyllos | white adder's-mouth | Orchidaceae | CT MA ME NH VT | Yes | Orchids and related plants | Orchids | |
| Malaxis unifolia | green adder's-mouth | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Malus baccata | Siberian crab apple | Rosaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Malus floribunda | Japanese flowering crab apple | Rosaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Malus prunifolia | pear-leaved crab apple | Rosaceae | CT MA ME NH VT | No | Woody Plants | Broad-leaved woody plants | |
| Malus pumila | cultivated apple | Rosaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Malus sieboldii | Toringo crab apple | Rosaceae | MA VT | No | Woody Plants | Broad-leaved woody plants | |
| Malva alcea | vervain mallow | Malvaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Malva moschata | musk mallow | Malvaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Malva neglecta | common mallow | Malvaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Malva parviflora | little mallow | Malvaceae | MA ME | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Malva rotundifolia | low mallow | Malvaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Malvastrum coromandelianum | three-lobed false mallow | Malvaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Malva sylvestris | high mallow | Malvaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Malva verticillata | whorled mallow | Malvaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Marrubium vulgare | white horehound | Lamiaceae | CT MA ME RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Marsilea quadrifolia | European water-clover | Marsileaceae | CT MA ME | No | Ferns; Aquatic plants | True ferns and moonworts; Water plants with leaves and stems | |
| Matricaria chamomilla | wild chamomile | Asteraceae | CT MA ME RI | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Matricaria discoidea | rayless chamomile | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Matteuccia struthiopteris | fiddlehead fern, ostrich fern | Onocleaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Mazus miquelii | creeping mazus | Phrymaceae | MA ME | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Mazus pumilus | Japanese mazus | Phrymaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Medeola virginiana | Indian cucumber root | Liliaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Medicago arabica | spotted medick | Fabaceae | CT MA ME RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Medicago disciformis | veinless medick | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Medicago falcata | yellow medick | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Medicago laciniata | cut-leaved medick | Fabaceae | MA ME | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Medicago lupulina | black medick | Fabaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Medicago minima | bur medick | Fabaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Medicago monantha | single-flowered medick | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Medicago polymorpha | toothed medick | Fabaceae | CT MA ME VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Medicago praecox | Mediterranean medick | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Medicago rigidula | Tifton medick | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Medicago sativa | purple medick | Fabaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Melampyrum lineare | cow-wheat | Orobanchaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Melilotus albus | white sweet-clover | Fabaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Melilotus indicus | Indian sweet-clover | Fabaceae | MA ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Melilotus officinalis | yellow sweet-clover | Fabaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Melissa officinalis | lemon-balm | Lamiaceae | CT MA RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Menispermum canadense | Canada moonseed | Menispermaceae | CT MA VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Mentha aquatica | water mint | Lamiaceae | CT MA ME RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Mentha arvensis | ginger mint | Lamiaceae | CT MA ME RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Mentha canadensis | American wild mint | Lamiaceae | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Mentha longifolia | horse mint | Lamiaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Mentha spicata | spearmint | Lamiaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Mentzelia oligosperma | stickleaf mentzelia | Loasaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Menyanthes trifoliata | buck-bean | Menyanthaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Mercurialis annua | annual mercury | Euphorbiaceae | MA ME | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Mertensia maritima | seaside bluebells | Boraginaceae | MA ME NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Mertensia virginica | eastern bluebells | Boraginaceae | MA ME VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Mibora minima | early sand grass | Poaceae | MA | No | Grass-like plants | True grasses | |
| Micranthes foliolosa | naked-bulbil small-flowered-saxifrage | Saxifragaceae | ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Micranthes pensylvanica | swamp small-flowered-saxifrage | Saxifragaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Micranthes virginiensis | early small-flowered-saxifrage | Saxifragaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Microseris douglasii | Douglas' silverpuffs | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Microstegium vimineum | Japanese stiltgrass | Poaceae | CT MA RI | No | Grass-like plants | True grasses | |
| Mikania scandens | climbing hempvine | Asteraceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Milium effusum | millet grass | Poaceae | CT MA ME NH VT | Yes | Grass-like plants | True grasses | |
| Mimulus alatus | winged monkey-flower | Phrymaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Mimulus brevipes | wide-throated monkey-flower | Phrymaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Mimulus guttatus | seep monkey-flower | Phrymaceae | CT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Mimulus moschatus | musky monkey-flower | Phrymaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Mimulus ringens | Allegheny monkey-flower | Phrymaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Minuartia caroliniana | pine barren sandplant | Caryophyllaceae | RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Minuartia glabra | Appalachian sandplant | Caryophyllaceae | CT ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Minuartia marcescens | serpentine sandplant | Caryophyllaceae | VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Minuartia michauxii | Michaux's sandplant | Caryophyllaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Minuartia rubella | boreal sandplant | Caryophyllaceae | ME VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Mirabilis albida | pale umbrella-wort | Nyctaginaceae | CT MA ME VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Mirabilis hirsuta | hairy umbrella-wort | Nyctaginaceae | CT MA ME VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Mirabilis jalapa | four o'clock umbrella-wort | Nyctaginaceae | CT VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Mirabilis linearis | narrow-leaved umbrella-wort | Nyctaginaceae | CT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Mirabilis nyctaginea | heart-leaved umbrella-wort | Nyctaginaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Miscanthus sacchariflorus | Amur silvergrass | Poaceae | CT MA ME | No | Grass-like plants | True grasses | |
| Miscanthus sinensis | Chinese silvergrass | Poaceae | CT MA RI | No | Grass-like plants | True grasses | |
| Misopates orontium | lesser-snapdragon | Plantaginaceae | CT ME | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Mitchella repens | partridge-berry | Rubiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants; Woody Plants | Other herbaceous, flowering plants with opposite, whorled or no leaves; Broad-leaved woody plants | |
| Mitella diphylla | two-leaf mitrewort, two-leaved bishop's-cap | Saxifragaceae | CT MA NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Mitella nuda | naked bishop's-cap, naked miterwort | Saxifragaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Mitella prostrata | prostrate bishop's-cap | Saxifragaceae | CT VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Modiola caroliniana | Carolina bristle-mallow | Malvaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Moehringia lateriflora | blunt-leaved grove-sandwort | Caryophyllaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Moehringia macrophylla | large-leaved grove-sandwort | Caryophyllaceae | CT MA VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Molinia caerulea | purple moorgrass | Poaceae | CT MA ME RI VT | No | Grass-like plants | True grasses | |
| Mollugo verticillata | green carpetweed | Molluginaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Momordica charantia | bitter-melon | Cucurbitaceae | CT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Monarda clinopodia | basil bee-balm | Lamiaceae | CT MA RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Monarda didyma | scarlet bee-balm | Lamiaceae | CT MA ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Monarda fistulosa | wild bee-balm, wild bergamot | Lamiaceae | CT MA ME NH RI VT | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Monarda media | purple bee-balm | Lamiaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Monarda punctata | spotted bee-balm | Lamiaceae | CT MA VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Moneses uniflora | one-flowered-shinleaf, single delight | Ericaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Monolepis nuttalliana | Nuttall's poverty-weed | Amaranthaceae | MA ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Mononeuria groenlandica | Greenland stitchwort, mountain sandplant | Caryophyllaceae | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Monotropa uniflora | one-flowered Indian-pipe | Ericaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Montia fontana | water montia | Portulacaceae | ME | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Montia linearis | narrow-leaved montia | Portulacaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Morella caroliniensis | small bayberry | Myricaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Morus alba | white mulberry | Moraceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Morus rubra | red mulberry | Moraceae | CT MA RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Muhlenbergia alopecuroides | bristly wolfstail | Poaceae | ME | Yes | Grass-like plants | True grasses | |
| Muhlenbergia capillaris | hair-awned muhly | Poaceae | CT MA | Yes | Grass-like plants | True grasses | |
| Muhlenbergia frondosa | wire-stemmed muhly | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Muhlenbergia glomerata | spike muhly | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Muhlenbergia mexicana | Mexican muhly | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Muhlenbergia racemosa | marsh muhly | Poaceae | ME NH | Yes | Grass-like plants | True grasses | |
| Muhlenbergia richardsonis | matted muhly | Poaceae | ME | Yes | Grass-like plants | True grasses | |
| Muhlenbergia schreberi | nimblewill muhly | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Muhlenbergia sobolifera | rock muhly | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Muhlenbergia sylvatica | woodland muhly | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Muhlenbergia tenuiflora | slender muhly | Poaceae | CT MA NH VT | Yes | Grass-like plants | True grasses | |
| Muhlenbergia uniflora | bog muhly | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Mulgedium pulchellum | Russia blue lettuce | Asteraceae | MA ME | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Muscari botryoides | common grape-hyacinth | Hyacinthaceae | CT MA NH VT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Muscari neglectum | starch grape-hyacinth | Hyacinthaceae | CT MA | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Mycelis muralis | wall-lettuce | Asteraceae | MA ME NH VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Myosotis arvensis | field forget-me-not | Boraginaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Myosotis discolor | yellow-and-blue forget-me-not | Boraginaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Myosotis laxa | smaller forget-me-not | Boraginaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Myosotis scorpioides | water forget-me-not | Boraginaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Myosotis stricta | blue forget-me-not | Boraginaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Myosotis sylvatica | woodland forget-me-not | Boraginaceae | MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Myosotis verna | spring forget-me-not | Boraginaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Myosoton aquaticum | giant-chickweed | Caryophyllaceae | CT MA NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Myosurus minimus | tiny mousetail | Ranunculaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Myrica gale | sweetgale | Myricaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Myriophyllum alterniflorum | alternate-flowered water-milfoil | Haloragaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Myriophyllum aquaticum | Parrot's-feather water-milfoil | Haloragaceae | CT | No | Aquatic plants | Water plants with leaves and stems | |
| Myriophyllum farwellii | Farwell's water-milfoil | Haloragaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Myriophyllum heterophyllum | variable-leaved water-milfoil | Haloragaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Myriophyllum humile | low water-milfoil | Haloragaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants; Aquatic plants | Other herbaceous, flowering plants with opposite, whorled or no leaves; Water plants with leaves and stems | |
| Myriophyllum pinnatum | cut-leaved water-milfoil | Haloragaceae | CT MA RI | Yes | Aquatic plants | Water plants with leaves and stems | |
| Myriophyllum sibiricum | northern water-milfoil | Haloragaceae | CT MA ME NH VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Myriophyllum spicatum | Eurasian water-milfoil | Haloragaceae | CT MA ME NH VT | No | Aquatic plants | Water plants with leaves and stems | |
| Myriophyllum tenellum | slender water-milfoil | Haloragaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants; Aquatic plants | Other herbaceous, flowering plants with alternate leaves; Water plants with leaves and stems | |
| Myriophyllum verticillatum | whorled water-milfoil | Haloragaceae | CT MA ME NH VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Myrrhis odorata | anise | Apiaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Nabalus albus | white rattlesnake-root | Asteraceae | CT MA ME NH VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Nabalus altissimus | tall rattlesnake-root | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Nabalus boottii | Boott's rattlesnake-root | Asteraceae | ME NH VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Nabalus racemosus | glaucous rattlesnake-root | Asteraceae | ME VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Nabalus serpentarius | lion's-foot rattlesnake-root | Asteraceae | CT MA NH RI | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Nabalus trifoliolatus | three-leaved rattlesnake-root | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Najas flexilis | nodding waternymph, wavy waternymph | Hydrocharitaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Najas gracillima | slender waternymph | Hydrocharitaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Najas guadalupensis | Guadalupe waternymph | Hydrocharitaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Najas minor | brittle waternymph | Hydrocharitaceae | CT MA ME NH VT | No | Aquatic plants | Water plants with leaves and stems | |
| Napaea dioica | glade-mallow | Malvaceae | ME VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Narcissus poeticus | poet's daffodil | Amaryllidaceae | CT MA ME VT | No | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Narcissus pseudonarcissus | common daffodil | Amaryllidaceae | CT MA NH RI | No | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Nardus stricta | doormat grass | Poaceae | MA NH VT | No | Grass-like plants | True grasses | |
| Nasturtium microphyllum | one-rowed water-cress | Brassicaceae | CT MA ME NH RI VT | No | Aquatic plants; All other flowering non-woody plants | Water plants with leaves and stems; Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Nasturtium officinale | nasturtium, two-rowed water-cress | Brassicaceae | CT MA ME NH RI VT | No | Aquatic plants; All other flowering non-woody plants | Water plants with leaves and stems; Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Navarretia leucocephala | white-flowered pincushion-plant | Polemoniaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Nelumbo lutea | American lotus | Nelumbonaceae | CT MA ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Neottia auriculata | auricled twayblade | Orchidaceae | ME NH VT | Yes | Orchids and related plants | Orchids | |
| Neottia bifolia | southern twayblade | Orchidaceae | MA VT | Yes | Orchids and related plants | Orchids | |
| Neottia convallarioides | broad-leaved twayblade | Orchidaceae | ME NH VT | Yes | Orchids and related plants | Orchids | |
| Neottia cordata | heart-leaved twayblade | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Nepeta cataria | catnip | Lamiaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Neslia paniculata | yellow ball-mustard | Brassicaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Nicandra physalodes | apple-of-Peru | Solanaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Nicotiana alata | Jasmine tobacco | Solanaceae | CT MA ME | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Nicotiana langsdorffii | flowering tobacco | Solanaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Nicotiana longiflora | long-flowered tobacco | Solanaceae | CT NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Nicotiana quadrivalvis | Indian tobacco | Solanaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Nicotiana rustica | Aztec tobacco | Solanaceae | CT MA NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Nicotiana tabacum | cultivated tobacco | Solanaceae | CT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Nigella damascena | devil-in-the-bush | Ranunculaceae | CT MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Nigella sativa | black-cumin | Ranunculaceae | CT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Nipponanthemum nipponicum | Nippon-daisy | Asteraceae | CT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Nonea rosea | rose monk's-wort | Boraginaceae | ME | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Nuphar advena | immigrant pond-lily | Nymphaeaceae | CT ME | Yes | Aquatic plants | Water plants with leaves and stems | |
| Nuphar microphylla | small-leaved pond-lily | Nymphaeaceae | CT MA ME NH VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Nuphar variegata | bullhead pond-lily, yellow pond-lily | Nymphaeaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Nuttallanthus canadensis | oldfield-toadflax | Plantaginaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Nymphaea leibergii | dwarf water-lily | Nymphaeaceae | ME VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Nymphaea odorata | white water-lily | Nymphaeaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Nymphaea tuberosa | tuberous water-lily | Nymphaeaceae | CT MA ME NH VT | Yes and no (some introduced) | Aquatic plants | Water plants with leaves and stems | |
| Nymphoides cordata | little floating-heart | Menyanthaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Nymphoides peltata | yellow floating-heart | Menyanthaceae | CT MA RI VT | No | Aquatic plants | Water plants with leaves and stems | |
| Nyssa sylvatica | black-gum, black tupelo | Cornaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Ocimum basilicum | sweet basil | Lamiaceae | CT MA RI | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Oclemena acuminata | sharp-toothed nodding-aster, whorled aster | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Oclemena nemoralis | bog aster, bog nodding-aster | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Odontites vernus | red false bartsia | Orobanchaceae | MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Oenothera biennis | common evening-primrose | Onagraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Oenothera curtiflora | small-flowered bee-blossom | Onagraceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Oenothera filiformis | bee-blossom | Onagraceae | CT MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Oenothera fruticosa | narrow-leaved evening-primrose | Onagraceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Oenothera gaura | biennial bee-blossom | Onagraceae | CT MA VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Oenothera glazioviana | garden evening-primrose | Onagraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Oenothera grandiflora | large-flowered evening-primrose | Onagraceae | CT VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Oenothera laciniata | cut-leaved evening-primrose | Onagraceae | CT MA ME VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Oenothera nutans | nodding evening-primrose | Onagraceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Oenothera oakesiana | Oakes' evening-primrose | Onagraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Oenothera parviflora | small-flowered evening-primrose | Onagraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Oenothera perennis | little evening-primrose | Onagraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Oenothera pilosella | meadow evening-primrose | Onagraceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Oenothera serrulata | yellow evening-primrose | Onagraceae | VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Oenothera villosa | hairy evening-primrose | Onagraceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Oligoneuron album | white flat-topped-goldenrod | Asteraceae | CT MA NH VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Oligoneuron rigidum | stiff flat-topped-goldenrod | Asteraceae | CT MA RI | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Omalotheca supina | alpine arctic-cudweed | Asteraceae | ME NH | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Omalotheca sylvatica | woodland arctic-cudweed | Asteraceae | ME NH VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Onobrychis viciifolia | Sanfoin | Fabaceae | MA VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Onoclea sensibilis | sensitive fern | Onocleaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Onopordum acanthium | Scotch cotton-thistle | Asteraceae | CT MA RI VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Onosmodium bejariense | soft-haired false gromwell | Boraginaceae | CT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Onosmodium virginianum | eastern false gromwell | Boraginaceae | CT MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ophioglossum pusillum | northern adder's-tongue fern | Ophioglossaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Opuntia humifusa | eastern prickly-pear | Cactaceae | CT MA NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Origanum majorana | sweet marjoram | Lamiaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Origanum vulgare | wild marjoram | Lamiaceae | CT MA VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Ornithogalum nutans | nodding star-of-Bethlehem | Hyacinthaceae | CT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Ornithogalum umbellatum | nap-at-noon | Hyacinthaceae | CT MA ME NH RI VT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Ornithopus sativus | common bird's-foot | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Orobanche minor | lesser broom-rape | Orobanchaceae | VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Orobanche uniflora | one-flowered broom-rape | Orobanchaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Orontium aquaticum | golden-club | Araceae | CT MA RI | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Orthilia secunda | one-sided-shinleaf | Ericaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Oryzopsis asperifolia | roughleaf ricegrass, white-grained rice grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Osmorhiza berteroi | mountain sweet-cicely | Apiaceae | ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Osmorhiza claytonii | bland sweet-cicely | Apiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Osmorhiza depauperata | blunt-fruited sweet-cicely | Apiaceae | ME VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Osmorhiza longistylis | long-styled sweet-cicely | Apiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Osmunda claytoniana | interrupted fern | Osmundaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Osmunda regalis | royal fern | Osmundaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Osmundastrum cinnamomeum | cinnamon fern | Osmundaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Ostrya virginiana | hop-hornbeam | Betulaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Othocallis siberica | Siberian squill | Hyacinthaceae | MA NH | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Oxalis corniculata | creeping yellow wood sorrel | Oxalidaceae | CT MA ME NH VT | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Oxalis dillenii | slender yellow wood sorrel | Oxalidaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Oxalis florida | flowering yellow wood sorrel | Oxalidaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Oxalis intermedia | West Indian wood sorrel | Oxalidaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Oxalis montana | northern wood sorrel | Oxalidaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Oxalis stricta | common yellow wood sorrel | Oxalidaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Oxalis violacea | violet wood sorrel | Oxalidaceae | CT MA RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Oxyria digyna | mountain-sorrel | Polygonaceae | NH | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Oxytropis campestris | St. John River oxytrope | Fabaceae | ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Pachysandra terminalis | Japanese mountain-spurge, pachysandra | Buxaceae | CT MA NH | No | Woody Plants | Broad-leaved woody plants | |
| Packera aurea | golden groundsel, golden ragwort | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Packera obovata | roundleaf ragwort, running groundsel | Asteraceae | CT MA NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Packera paupercula | balsam groundsel | Asteraceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Packera schweinitziana | New England groundsel | Asteraceae | ME NH VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Paeonia lactiflora | Chinese peony | Paeoniaceae | MA VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Paeonia officinalis | common peony | Paeoniaceae | MA VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Palafoxia texana | Texas palafox | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Panax quinquefolius | American ginseng | Apiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Panax trifolius | dwarf ginseng | Apiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Panicum amarum | bitter panicgrass | Poaceae | CT MA RI | Yes | Grass-like plants | True grasses | |
| Panicum capillare | witch panicgrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Panicum dichotomiflorum | fall panicgrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Panicum flexile | wiry panicgrass | Poaceae | MA VT | Yes | Grass-like plants | True grasses | |
| Panicum miliaceum | Proso millet | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Panicum philadelphicum | Philadelphia panicgrass | Poaceae | CT MA NH RI VT | Yes | Grass-like plants | True grasses | |
| Panicum tuckermannii | Tuckerman's panicgrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Panicum verrucosum | warty panicgrass | Poaceae | CT MA RI | Yes | Grass-like plants | True grasses | |
| Panicum virgatum | switch panicgrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Papaver dubium | long-podded poppy | Papaveraceae | CT MA RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Papaver rhoeas | corn poppy | Papaveraceae | CT MA ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Papaver somniferum | opium poppy | Papaveraceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Pappophorum vaginatum | whiplash pappusgrass | Poaceae | ME | Yes | Grass-like plants | True grasses | |
| Parathelypteris noveboracensis | New York fern | Thelypteridaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Parathelypteris simulata | Massachusetts fern | Thelypteridaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Parietaria judaica | spreading pellitory | Urticaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Parietaria pensylvanica | Pennsylvania pellitory | Urticaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Parnassia glauca | fen grass-of-Parnassus | Parnassiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Paronychia argyrocoma | silvery whitlow-wort | Caryophyllaceae | MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Paronychia canadensis | smooth forked whitlow-wort | Caryophyllaceae | CT MA NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Paronychia fastigiata | hairy forked whitlow-wort | Caryophyllaceae | CT MA ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Parthenium hysterophorus | Santa Maria feverfew | Asteraceae | CT MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Parthenium integrifolium | wild feverfew | Asteraceae | CT MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Parthenocissus inserta | thicket-creeper | Vitaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Parthenocissus quinquefolia | Virginia-creeper, woodbine | Vitaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Parthenocissus tricuspidata | Boston-ivy | Vitaceae | CT MA ME VT | No | Woody Plants | Broad-leaved woody plants | |
| Pascopyrum smithii | western wheat grass | Poaceae | MA NH | Yes | Grass-like plants | True grasses | |
| Paspalum laeve | field beadgrass | Poaceae | CT MA | Yes | Grass-like plants | True grasses | |
| Paspalum setaceum | slender beadgrass | Poaceae | CT MA NH RI VT | Yes | Grass-like plants | True grasses | |
| Pastinaca sativa | wild parsnip | Apiaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Paulownia tomentosa | empress-tree, princess-tree | Paulowniaceae | CT MA RI | No | Woody Plants | Broad-leaved woody plants | |
| Pedicularis canadensis | Canadian lousewort, forest lousewort | Orobanchaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Pedicularis furbishiae | Furbish's lousewort | Orobanchaceae | ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Pedicularis lanceolata | swamp lousewort | Orobanchaceae | CT MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Pellaea atropurpurea | purple cliff-brake | Pteridaceae | CT MA NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Pellaea glabella | slender cliff-brake | Pteridaceae | CT VT | Yes | Ferns | True ferns and moonworts | |
| Peltandra virginica | green arrow-arum | Araceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Penstemon barbatus | beard-lip beardtongue | Plantaginaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Penstemon calycosus | long-sepaled beardtongue | Plantaginaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Penstemon digitalis | foxglove beardtongue | Plantaginaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Penstemon grandiflorus | large beardtongue | Plantaginaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Penstemon hirsutus | northeastern beardtongue | Plantaginaceae | CT MA ME RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Penstemon laevigatus | eastern smooth beardtongue | Plantaginaceae | CT MA RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Penstemon pallidus | eastern white beardtongue | Plantaginaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Penstemon tubiflorus | tube beardtongue | Plantaginaceae | CT MA ME NH | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Penthorum sedoides | ditch-stonecrop | Penthoraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Perezia multiflora | perezia | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Perilla frutescens | perilla-mint | Lamiaceae | CT MA RI | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Periploca graeca | silkvine | Apocynaceae | CT RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Peritoma serrulata | stinking bee-plant | Cleomaceae | CT MA ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Persicaria amphibia | water smartweed | Polygonaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Persicaria arifolia | halberd-leaved smartweed | Polygonaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Persicaria careyi | Carey's smartweed | Polygonaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Persicaria chinensis | Chinese smartweed | Polygonaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Persicaria coccinea | scarlet smartweed | Polygonaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Persicaria hydropiper | water-pepper smartweed | Polygonaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Persicaria hydropiperoides | false water-pepper smartweed | Polygonaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Persicaria lapathifolia | dock-leaved smartweed | Polygonaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Persicaria longiseta | Oriental lady's-thumb smartweed | Polygonaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Persicaria maculosa | lady's-thumb smartweed | Polygonaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Persicaria minor | small smartweed | Polygonaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Persicaria nepalensis | Nepalese smartweed | Polygonaceae | CT MA ME | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Persicaria orientalis | prince's-feather smartweed | Polygonaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Persicaria pensylvanica | Pennsylvania smartweed | Polygonaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Persicaria perfoliata | Asiatic smartweed | Polygonaceae | CT MA RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Persicaria punctata | dotted smartweed | Polygonaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Persicaria puritanorum | Puritan smartweed | Polygonaceae | MA ME RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Persicaria robustior | stout dotted smartweed | Polygonaceae | CT MA ME NH RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Persicaria sagittata | arrow-leaved tearthumb | Polygonaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Persicaria setacea | bristly smartweed | Polygonaceae | MA RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Persicaria virginiana | jumpseed | Polygonaceae | CT MA NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Persicaria wallichii | garden smartweed | Polygonaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Petasites frigidus | northern sweet-coltsfoot | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Petasites hybridus | butterbur sweet-coltsfoot | Asteraceae | CT MA VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Petasites japonicus | Japanese sweet-coltsfoot | Asteraceae | ME | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Petrorhagia prolifera | proliferous childing-pink | Caryophyllaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Petrorhagia saxifraga | saxifrage childing-pink | Caryophyllaceae | MA ME NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Petroselinum crispum | parsley | Apiaceae | CT MA RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Petunia axillaris | garden petunia | Solanaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Petunia integrifolia | violet-flowered petunia | Solanaceae | CT MA ME NH RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Peucedanum palustre | milk-parsley | Apiaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Phacelia brachyloba | yellow-throated scorpion-weed | Boraginaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Phacelia distans | distant scorpion-weed | Boraginaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Phacelia egena | rock scorpion-weed | Boraginaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Phacelia linearis | thread-leaved scorpion-weed | Boraginaceae | CT ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Phacelia minor | wild scorpion-weed | Boraginaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Phacelia purshii | purple scorpion-weed | Boraginaceae | CT RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Phacelia tanacetifolia | lacy scorpion-weed | Boraginaceae | MA ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Phacelia viscida | tacky scorpion-weed | Boraginaceae | CT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Phalaris arundinacea | reed canary grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Phalaris canariensis | common canary grass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Phaseolus coccineus | scarlet bean | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Phaseolus polystachios | wild bean | Fabaceae | CT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Phaseolus vulgaris | kidney bean | Fabaceae | CT MA ME NH RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Phedimus spurius | false stonecrop | Crassulaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Phedimus stoloniferus | running false stonecrop | Crassulaceae | ME NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Phegopteris connectilis | long beech fern | Thelypteridaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Phegopteris hexagonoptera | broad beech fern | Thelypteridaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Phellodendron amurense | Amur corktree | Rutaceae | CT MA RI | No | Woody Plants | Broad-leaved woody plants | |
| Philadelphus coronarius | sweet mock-orange | Hydrangeaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Philadelphus inodorus | scentless mock-orange | Hydrangeaceae | CT MA RI | No | Woody Plants | Broad-leaved woody plants | |
| Philadelphus pubescens | hoary mock-orange | Hydrangeaceae | CT MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Phleum alpinum | mountain Timothy | Poaceae | ME NH | Yes | Grass-like plants | True grasses | |
| Phleum arenarium | sand Timothy | Poaceae | MA | No | Grass-like plants | True grasses | |
| Phleum pratense | common Timothy | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Phleum subulatum | Italian Timothy | Poaceae | MA | No | Grass-like plants | True grasses | |
| Phlox bifida | sand phlox | Polemoniaceae | VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Phlox divaricata | wild blue phlox | Polemoniaceae | CT VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Phlox drummondii | annual phlox | Polemoniaceae | CT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Phlox latifolia | mountain phlox | Polemoniaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Phlox maculata | spotted phlox, wild sweet-William | Polemoniaceae | CT ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Phlox paniculata | garden phlox, summer phlox | Polemoniaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Phlox pilosa | downy phlox | Polemoniaceae | CT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Phlox stolonifera | creeping phlox | Polemoniaceae | ME VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Phlox subulata | moss phlox | Polemoniaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Phragmites americanus | American reed | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Phragmites australis | common reed | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Phryma leptostachya | American lop-seed | Phrymaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Phyllodoce caerulea | purple mountain-heath | Ericaceae | ME NH | Yes | All other flowering non-woody plants; Woody Plants | Other herbaceous, flowering plants with alternate leaves; Broad-leaved woody plants | |
| Phyllostachys dulcis | sweet-shoot bamboo | Poaceae | MA | No | Grass-like plants | True grasses | |
| Physalis alkekengi | strawberry ground-cherry | Solanaceae | CT MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Physalis angulata | cut-leaved ground-cherry | Solanaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Physalis grisea | downy ground-cherry | Solanaceae | CT MA ME RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Physalis heterophylla | clammy ground-cherry | Solanaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Physalis longifolia | long-leaved ground-cherry | Solanaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Physalis philadelphica | Mexican ground-cherry | Solanaceae | MA VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Physalis pubescens | hairy ground-cherry | Solanaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Physalis virginiana | Virginia ground-cherry | Solanaceae | CT MA ME NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Physocarpus opulifolius | Atlantic ninebark | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Physostegia virginiana | obedient false dragonhead | Lamiaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Phytolacca americana | American pokeweed | Phytolaccaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Picea abies | Norway spruce | Pinaceae | CT MA ME NH RI VT | No | Woody Plants | Needle-leaved woody plants | |
| Picea glauca | white spruce | Pinaceae | CT MA ME NH RI VT | Yes | Woody Plants | Needle-leaved woody plants | |
| Picea mariana | black spruce | Pinaceae | CT MA ME NH RI VT | Yes | Woody Plants | Needle-leaved woody plants | |
| Picea rubens | red spruce | Pinaceae | CT MA ME NH VT | Yes | Woody Plants | Needle-leaved woody plants | |
| Picris hieracioides | hawkweed oxtongue | Asteraceae | CT MA ME VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Pieris floribunda | mountain fetterbush | Ericaceae | VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Pilea fontana | lesser clearweed | Urticaceae | CT MA RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Pilea pumila | Canada clearweed | Urticaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Pimpinella anisum | anise burnet-saxifrage | Apiaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Pimpinella saxifraga | solid-stemmed burnet-saxifrage | Apiaceae | CT MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Pinguicula vulgaris | violet butterwort | Lentibulariaceae | ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Pinus banksiana | Jack pine | Pinaceae | MA ME NH RI VT | Yes and no (some introduced) | Woody Plants | Needle-leaved woody plants | |
| Pinus mugo | Mugo pine | Pinaceae | MA NH | No | Woody Plants | Needle-leaved woody plants | |
| Pinus nigra | Austrian pine | Pinaceae | MA ME | No | Woody Plants | Needle-leaved woody plants | |
| Pinus resinosa | red pine | Pinaceae | CT MA ME NH RI VT | Yes | Woody Plants | Needle-leaved woody plants | |
| Pinus rigida | pitch pine | Pinaceae | CT MA ME NH RI VT | Yes | Woody Plants | Needle-leaved woody plants | |
| Pinus strobus | eastern white pine | Pinaceae | CT MA ME NH RI VT | Yes | Woody Plants | Needle-leaved woody plants | |
| Pinus sylvestris | Scotch pine | Pinaceae | CT MA ME NH RI VT | No | Woody Plants | Needle-leaved woody plants | |
| Pinus thunbergii | Japanese black pine | Pinaceae | MA | No | Woody Plants | Needle-leaved woody plants | |
| Piptatherum canadense | Canada mountain-rice grass | Poaceae | ME NH | Yes | Grass-like plants | True grasses | |
| Piptatherum pungens | short-awned mountain-rice grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Piptatherum racemosum | black-seeded mountain-rice grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Piptochaetium avenaceum | black-seeded spear grass | Poaceae | CT MA RI | Yes | Grass-like plants | True grasses | |
| Pisum sativum | garden pea | Fabaceae | CT MA ME NH | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Pityopsis falcata | sickle-leaved golden-aster, sickle-leaved silk-grass | Asteraceae | CT MA RI | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Plagiobothrys reticulatus | netted popcorn-flower | Boraginaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Plagiobothrys trachycarpus | rough-fruited popcorn-flower | Boraginaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Plantago arenaria | sand plantain | Plantaginaceae | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Plantago aristata | bracted plantain | Plantaginaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Plantago coronopus | buck's-horn plantain | Plantaginaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Plantago intermedia | many-seeded plantain | Plantaginaceae | CT MA ME NH RI | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Plantago lanceolata | English plantain | Plantaginaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Plantago major | common plantain | Plantaginaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Plantago maritima | seaside plantain | Plantaginaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Plantago media | hoary plantain | Plantaginaceae | CT MA ME NH RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Plantago patagonica | Pursh's plantain | Plantaginaceae | MA ME VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Plantago pusilla | dwarf plantain | Plantaginaceae | CT MA RI | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Plantago rugelii | Rugel's plantain | Plantaginaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Plantago virginica | pale-seeded plantain | Plantaginaceae | CT MA ME RI | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Platanthera aquilonis | north wind bog-orchid | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Platanthera blephariglottis | white-fringed bog-orchid | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Platanthera ciliaris | orange fringed bog-orchid | Orchidaceae | CT MA RI | Yes | Orchids and related plants | Orchids | |
| Platanthera clavellata | little club-spur bog-orchid | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Platanthera cristata | crested orange bog-orchid | Orchidaceae | MA | Yes | Orchids and related plants | Orchids | |
| Platanthera dilatata | white northern bog-orchid | Orchidaceae | MA ME NH VT | Yes | Orchids and related plants | Orchids | |
| Platanthera flava | northern tubercled bog-orchid | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Platanthera grandiflora | greater purple fringed bog-orchid | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Platanthera hookeri | Hooker's bog-orchid | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Platanthera huronensis | Lake Huron bog green orchid | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Platanthera lacera | green fringed bog-orchid | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Platanthera leucophaea | eastern prairie white fringed bog-orchid | Orchidaceae | ME | Yes | Orchids and related plants | Orchids | |
| Platanthera macrophylla | large-leaved bog-orchid | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Platanthera obtusata | blunt-leaved bog-orchid | Orchidaceae | MA ME NH VT | Yes | Orchids and related plants | Orchids | |
| Platanthera orbiculata | round-leaved bog-orchid | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Platanthera psycodes | lesser purple fringed bog-orchid | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Platanus hybrida | London sycamore | Platanaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Platanus occidentalis | American sycamore | Platanaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Pluchea odorata | sweet-scented camphorweed | Asteraceae | CT MA NH RI | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Poa alsodes | grove blue grass | Poaceae | CT MA ME NH VT | Yes | Grass-like plants | True grasses | |
| Poa annua | annual blue grass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Poa bulbosa | bulbous blue grass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Poa chapmaniana | Chapman's blue grass | Poaceae | MA | No | Grass-like plants | True grasses | |
| Poa compressa | flat-stemmed blue grass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Poa glauca | glaucous blue grass | Poaceae | ME NH VT | Yes | Grass-like plants | True grasses | |
| Poa interior | interior blue grass | Poaceae | VT | Yes | Grass-like plants | True grasses | |
| Poa laxa | wavy blue grass | Poaceae | ME NH VT | Yes | Grass-like plants | True grasses | |
| Poa nemoralis | wood blue grass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Poa palustris | fowl blue grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Poa pratensis | Kentucky blue grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Poa saltuensis | weak spear grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Poa secunda | curly blue grass | Poaceae | ME | Yes | Grass-like plants | True grasses | |
| Poa trivialis | rough-sheathed blue grass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Podophyllum peltatum | mandrake, May-apple | Berberidaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Podostemum ceratophyllum | horn-leaved riverweed | Podostemaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Pogonia ophioglossoides | rose pogonia | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Polanisia dodecandra | red-whiskered clammyweed | Cleomaceae | CT MA NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Polemonium caeruleum | blue Jacob's-ladder | Polemoniaceae | ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Polemonium micranthum | annual Jacob's-ladder | Polemoniaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Polemonium reptans | spreading Jacob's-ladder | Polemoniaceae | CT MA NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Polemonium vanbruntiae | bog Jacob's-ladder | Polemoniaceae | ME VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Polycarpon tetraphyllum | four-leaved manyseed | Caryophyllaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Polycnemum majus | giant needle-leaf | Amaranthaceae | NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Polygala ambigua | alternate milkwort | Polygalaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Polygala cruciata | drum-heads milkwort | Polygalaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Polygala nuttallii | Nuttall's milkwort | Polygalaceae | CT MA RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Polygala paucifolia | fringed milkwort, gaywings | Polygalaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Polygala polygama | racemed milkwort | Polygalaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Polygala sanguinea | blood milkwort, purple milkwort | Polygalaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Polygala senega | Seneca milkwort | Polygalaceae | CT MA ME RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Polygala verticillata | whorled milkwort | Polygalaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Polygonatum biflorum | King Solomon's-seal | Ruscaceae | CT MA ME NH VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Polygonatum latifolium | broad-leaved Solomon's-seal | Ruscaceae | MA NH VT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Polygonatum pubescens | hairy Solomon's-seal | Ruscaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Polygonum achoreum | leathery knotweed | Polygonaceae | ME VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Polygonum arenarium | European knotweed | Polygonaceae | RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Polygonum articulatum | coastal jointed knotweed | Polygonaceae | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Polygonum aviculare | dooryard knotweed | Polygonaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Polygonum bellardii | Bellard's knotweed | Polygonaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Polygonum buxiforme | prairie knotweed | Polygonaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Polygonum douglasii | Douglas's knotweed | Polygonaceae | ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Polygonum erectum | upright knotweed | Polygonaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Polygonum fowleri | Fowler's knotweed | Polygonaceae | ME | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Polygonum glaucum | seaside knotweed | Polygonaceae | CT MA RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Polygonum oxyspermum | Ray's knotweed | Polygonaceae | ME | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Polygonum ramosissimum | yellow-flowered knotweed | Polygonaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Polygonum tenue | slender knotweed | Polygonaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Polymnia canadensis | white-flowered leaf-cup | Asteraceae | CT VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Polypodium appalachianum | Appalachian polypody | Polypodiaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Polypodium virginianum | rock polypody | Polypodiaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Polypogon monspeliensis | annual rabbit's-foot grass | Poaceae | CT MA ME NH | No | Grass-like plants | True grasses | |
| Polypogon viridis | beardless rabbit's-foot grass | Poaceae | CT | No | Grass-like plants | True grasses | |
| Polystichum acrostichoides | Christmas fern | Dryopteridaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Polystichum braunii | Braun's holly fern | Dryopteridaceae | CT MA ME NH VT | Yes | Ferns | True ferns and moonworts | |
| Pontederia cordata | pickerelweed | Pontederiaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Populus alba | white poplar | Salicaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Populus balsamifera | balsam poplar | Salicaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Populus deltoides | eastern cottonwood, necklace poplar | Salicaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Populus grandidentata | bigtooth aspen, big-toothed poplar | Salicaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Populus heterophylla | swamp poplar | Salicaceae | CT MA RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Populus nigra | black poplar | Salicaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Populus tremula | European poplar | Salicaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Populus tremuloides | quaking aspen, quaking poplar | Salicaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Portulaca grandiflora | cultivated purslane | Portulacaceae | CT MA NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Portulaca oleracea | common purslane | Portulacaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Potamogeton alpinus | alpine pondweed, reddish pondweed | Potamogetonaceae | MA ME NH VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton amplifolius | big-leaved pondweed | Potamogetonaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton berchtoldii | Berchtold's pondweed | Potamogetonaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton bicupulatus | snail-seed pondweed | Potamogetonaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton confervoides | alga-like pondweed, Tuckerman's pondweed | Potamogetonaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton crispus | curly pondweed | Potamogetonaceae | CT MA ME NH RI VT | No | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton epihydrus | ribbon-leaved pondweed | Potamogetonaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton foliosus | leafy pondweed | Potamogetonaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton friesii | flat-stalked pondweed | Potamogetonaceae | CT MA ME VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton gemmiparus | budding pondweed | Potamogetonaceae | CT MA ME NH RI | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton gramineus | grassy pondweed | Potamogetonaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton hillii | Hill's pondweed | Potamogetonaceae | CT MA VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton illinoensis | Illinois pondweed | Potamogetonaceae | CT MA VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton natans | floating pondweed | Potamogetonaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton nodosus | long-leaved pondweed | Potamogetonaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton oakesianus | Oakes' pondweed | Potamogetonaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton obtusifolius | blunt-leaved pondweed | Potamogetonaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton ogdenii | Ogden's pondweed | Potamogetonaceae | CT MA VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton perfoliatus | clasping-leaved pondweed | Potamogetonaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton praelongus | white-stemmed pondweed | Potamogetonaceae | CT MA ME NH VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton pulcher | spotted pondweed | Potamogetonaceae | CT MA ME NH RI | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton pusillus | small pondweed | Potamogetonaceae | CT MA ME VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton richardsonii | Richardson's pondweed | Potamogetonaceae | CT MA ME NH VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton robbinsii | Robbins' pondweed | Potamogetonaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton spirillus | northern snail-seed pondweed | Potamogetonaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton strictifolius | straight-leaved pondweed | Potamogetonaceae | CT MA ME VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton vaseyi | Vasey's pondweed | Potamogetonaceae | CT MA ME NH VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potamogeton zosteriformis | flat-stem pondweed | Potamogetonaceae | CT MA ME NH VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Potentilla alba | white cinquefoil | Rosaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Potentilla anglica | English cinquefoil | Rosaceae | ME | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Potentilla argentea | silver-leaved cinquefoil | Rosaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Potentilla canadensis | dwarf cinquefoil | Rosaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Potentilla erecta | erect cinquefoil | Rosaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Potentilla gracilis | graceful cinquefoil | Rosaceae | NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Potentilla inclinata | ashy cinquefoil | Rosaceae | CT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Potentilla indica | Indian-strawberry | Rosaceae | CT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Potentilla intermedia | downy cinquefoil | Rosaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Potentilla litoralis | coast cinquefoil | Rosaceae | ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Potentilla norvegica | Norwegian cinquefoil | Rosaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Potentilla pulcherrima | soft cinquefoil | Rosaceae | NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Potentilla recta | sulphur cinquefoil | Rosaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Potentilla reptans | creeping cinquefoil | Rosaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Potentilla rivalis | brook cinquefoil | Rosaceae | MA ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Potentilla robbinsiana | Robbins' cinquefoil | Rosaceae | NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Potentilla simplex | common cinquefoil, old-field cinquefoil | Rosaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Potentilla verna | spring cinquefoil | Rosaceae | CT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Primula japonica | Japanese primrose | Primulaceae | MA VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Primula laurentiana | bird's-eye primrose | Primulaceae | ME | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Primula mistassinica | Lake Mistassini primrose | Primulaceae | ME VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Primula veris | cowslip primrose | Primulaceae | CT MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Proboscidea louisianica | ram's-horn | Pedaliaceae | CT MA RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Proserpinaca palustris | marsh mermaid-weed | Haloragaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants; Aquatic plants | Other herbaceous, flowering plants with alternate leaves; Water plants with leaves and stems | |
| Proserpinaca pectinata | comb-leaved mermaid-weed | Haloragaceae | MA ME NH RI | Yes | All other flowering non-woody plants; Aquatic plants | Other herbaceous, flowering plants with alternate leaves; Water plants with leaves and stems | |
| Prunella laciniata | cut-leaved selfheal | Lamiaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Prunella vulgaris | common selfheal, heal-all | Lamiaceae | CT MA ME NH RI VT | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Prunus alleghaniensis | Allegheny plum | Rosaceae | CT MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Prunus americana | American plum | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Prunus avium | sweet cherry | Rosaceae | CT MA ME RI | No | Woody Plants | Broad-leaved woody plants | |
| Prunus cerasifera | cherry plum | Rosaceae | MA NH | No | Woody Plants | Broad-leaved woody plants | |
| Prunus cerasus | sour cherry | Rosaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Prunus domestica | European plum | Rosaceae | CT MA NH | No | Woody Plants | Broad-leaved woody plants | |
| Prunus hortulana | Hortulan plum | Rosaceae | MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Prunus insititia | Damson plum | Rosaceae | CT MA ME NH VT | No | Woody Plants | Broad-leaved woody plants | |
| Prunus mahaleb | Mahaleb cherry | Rosaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Prunus maritima | beach plum | Rosaceae | CT MA ME NH RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Prunus nigra | Canada plum | Rosaceae | CT MA ME VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Prunus pensylvanica | pin cherry | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Prunus persica | peach | Rosaceae | CT MA ME RI | No | Woody Plants | Broad-leaved woody plants | |
| Prunus pumila | dwarf sand plum | Rosaceae | MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Prunus serotina | black cherry | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Prunus serrulata | Japanese flowering cherry | Rosaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Prunus spinosa | blackthorn plum | Rosaceae | CT MA ME | No | Woody Plants | Broad-leaved woody plants | |
| Prunus susquehanae | Appalachian sand plum | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Prunus virginiana | choke cherry | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Pseudabutilon stuckertii | South American false velvetleaf | Malvaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Pseudognaphalium macounii | Macoun's rabbit-tobacco | Asteraceae | CT MA ME NH VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Pseudognaphalium micradenium | Weatherby's rabbit-tobacco | Asteraceae | MA ME NH | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Pseudognaphalium obtusifolium | blunt-leaved rabbit-tobacco | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Pseudolycopodiella caroliniana | slender false bog-clubmoss | Lycopodiaceae | MA | Yes | Ferns | Clubmosses and relatives, plus quillworts | |
| Pseudosasa japonica | Japanese arrow bamboo | Poaceae | CT | No | Grass-like plants | True grasses | |
| Pseudotsuga menziesii | coast Douglas-fir | Pinaceae | CT MA | No | Woody Plants | Needle-leaved woody plants | |
| Ptelea trifoliata | common hoptree | Rutaceae | CT MA NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Pteridium aquilinum | bracken fern | Dennstaedtiaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Pterospora andromedea | pine-drops | Ericaceae | NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ptilimnium capillaceum | Atlantic mock bishop-weed | Apiaceae | CT MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Puccinellia distans | spreading alkali grass | Poaceae | CT MA ME VT | Yes | Grass-like plants | True grasses | |
| Puccinellia fasciculata | saltmarsh alkali grass | Poaceae | CT MA ME RI | Yes | Grass-like plants | True grasses | |
| Puccinellia maritima | seaside alkali grass | Poaceae | CT MA ME NH RI | No | Grass-like plants | True grasses | |
| Puccinellia nuttalliana | Nuttall's alkali grass | Poaceae | ME VT | Yes | Grass-like plants | True grasses | |
| Puccinellia pumila | tundra alkali grass | Poaceae | CT MA ME NH RI | Yes | Grass-like plants | True grasses | |
| Pueraria montana | kudzu | Fabaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Pulmonaria saccharata | Bethlehem lungwort | Boraginaceae | CT VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Pycnanthemum incanum | hoary mountain-mint | Lamiaceae | CT MA NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Pycnanthemum muticum | broad-leaved mountain-mint, clustered mountain-mint | Lamiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Pycnanthemum tenuifolium | narrow-leaved mountain-mint | Lamiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Pycnanthemum torrei | Torrey's mountain-mint | Lamiaceae | CT NH | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Pycnanthemum verticillatum | whorled mountain-mint | Lamiaceae | CT MA RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Pycnanthemum virginianum | Virginia mountain-mint | Lamiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Pyrola americana | American shinleaf, American wintergreen | Ericaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Pyrola asarifolia | pink shinleaf | Ericaceae | MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Pyrola chlorantha | green-flowered shinleaf | Ericaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Pyrola elliptica | elliptic-leaved shinleaf | Ericaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Pyrola minor | little shinleaf | Ericaceae | ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Pyrus calleryana | Bradford pear | Rosaceae | CT MA NH | No | Woody Plants | Broad-leaved woody plants | |
| Pyrus communis | common pear | Rosaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Quercus alba | eastern white oak | Fagaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Quercus bicolor | swamp white oak | Fagaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Quercus cerris | European turkey oak | Fagaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Quercus coccinea | scarlet oak | Fagaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Quercus ilicifolia | scrub oak | Fagaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Quercus imbricaria | shingle oak | Fagaceae | MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Quercus macrocarpa | burr oak | Fagaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Quercus montana | mountain chestnut oak | Fagaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Quercus muehlenbergii | chinkapin oak, yellow chestnut oak | Fagaceae | CT MA VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Quercus palustris | pin oak | Fagaceae | CT MA ME RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Quercus phellos | willow oak | Fagaceae | CT | Yes | Woody Plants | Broad-leaved woody plants | |
| Quercus prinoides | dwarf chestnut oak | Fagaceae | CT MA NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Quercus robur | English oak | Fagaceae | MA ME NH RI | No | Woody Plants | Broad-leaved woody plants | |
| Quercus rubra | northern red oak | Fagaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Quercus stellata | post oak | Fagaceae | CT MA RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Quercus velutina | black oak | Fagaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Ranunculus abortivus | kidney-leaved crowfoot, little-leaf buttercup | Ranunculaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ranunculus acris | tall buttercup, tall crowfoot | Ranunculaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ranunculus allegheniensis | Allegheny crowfoot | Ranunculaceae | CT MA RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ranunculus ambigens | water-plantain crowfoot | Ranunculaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ranunculus aquatilis | white water buttercup, white water crowfoot | Ranunculaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Ranunculus bulbosus | bulbous crowfoot, St. Anthony's turnip | Ranunculaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ranunculus caricetorum | swamp buttercup, swamp crowfoot | Ranunculaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ranunculus cymbalaria | seaside buttercup, seaside crowfoot | Ranunculaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ranunculus fascicularis | early crowfoot | Ranunculaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Ranunculus flabellaris | greater yellow water crowfoot, yellow water buttercup | Ranunculaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ranunculus flammula | creeping crowfoot, creeping spearwort | Ranunculaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ranunculus gmelinii | lesser yellow water crowfoot | Ranunculaceae | ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ranunculus hispidus | hispid crowfoot | Ranunculaceae | CT MA RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ranunculus micranthus | small-flowered crowfoot | Ranunculaceae | CT MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ranunculus pensylvanicus | bristly crowfoot | Ranunculaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ranunculus recurvatus | hooked buttercup, hooked crowfoot | Ranunculaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ranunculus repens | creeping buttercup, spot-leaved crowfoot | Ranunculaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ranunculus rhomboideus | prairie crowfoot | Ranunculaceae | MA RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ranunculus sardous | hairy crowfoot | Ranunculaceae | RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ranunculus sceleratus | cursed crowfoot | Ranunculaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Raphanus raphanistrum | wild radish | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Raphanus sativus | cultivated radish | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Rapistrum rugosum | annual bastard-cabbage | Brassicaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Ratibida columnifera | prairie Mexican-hat | Asteraceae | CT MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Ratibida pinnata | gray-headed Mexican-hat | Asteraceae | CT MA VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Reseda alba | white upright mignonette | Resedaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Reseda lutea | yellow upright mignonette | Resedaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Reseda luteola | dyer's mignonette | Resedaceae | CT MA NH RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Reseda odorata | garden mignonette | Resedaceae | CT MA ME | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Rhamnus alnifolia | alder-leaved buckthorn | Rhamnaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rhamnus cathartica | European buckthorn | Rhamnaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Rhamnus davurica | Dahurian buckthorn | Rhamnaceae | CT MA RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Rhamnus utilis | Chinese buckthorn | Rhamnaceae | CT | No | Woody Plants | Broad-leaved woody plants | |
| Rheum rhabarbarum | garden rhubarb | Polygonaceae | CT MA ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Rhexia mariana | Maryland meadow-beauty | Melastomataceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Rhexia virginica | Virginia meadow-beauty | Melastomataceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Rhinanthus alectorolophus | European yellow-rattle | Orobanchaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Rhinanthus minor | little yellow-rattle | Orobanchaceae | CT MA ME NH VT | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Rhodiola rosea | roseroot | Crassulaceae | CT ME VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Rhododendron calendulaceum | flame azalea | Ericaceae | CT MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Rhododendron canadense | Canada rosebay, rhodora | Ericaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rhododendron carolinianum | Carolina rhododendron | Ericaceae | CT MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Rhododendron catawbiense | Catawba rosebay | Ericaceae | CT MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Rhododendron groenlandicum | Labrador-tea | Ericaceae | Yes | Woody Plants | Broad-leaved woody plants | ||
| Rhododendron japonicum | Japanese azalea | Ericaceae | CT | No | Woody Plants | Broad-leaved woody plants | |
| Rhododendron lapponicum | Lapland rosebay | Ericaceae | ME NH | Yes | Woody Plants | Broad-leaved woody plants | |
| Rhododendron maximum | great rosebay, rhododendron | Ericaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rhododendron periclymenoides | pink azalea, pinxterbloom azalea | Ericaceae | CT MA NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rhododendron prinophyllum | early azalea | Ericaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rhododendron vaseyi | pink-shell azalea | Ericaceae | MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Rhododendron viscosum | clammy azalea | Ericaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rhodotypos scandens | black jetbead | Rosaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Rhus aromatica | fragrant sumac | Anacardiaceae | CT MA NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rhus copallinum | winged sumac | Anacardiaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rhus glabra | smooth sumac | Anacardiaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rhus hirta | staghorn sumac | Anacardiaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rhynchospora alba | white beaksedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Rhynchospora capillacea | needle beaksedge | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | All other grass-like plants | |
| Rhynchospora capitellata | brownish beaksedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Rhynchospora fusca | brown beaksedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Rhynchospora inundata | narrow-fruited beaksedge | Cyperaceae | MA RI | Yes | Grass-like plants | All other grass-like plants | |
| Rhynchospora macrostachya | tall beaksedge | Cyperaceae | CT MA ME RI | Yes | Grass-like plants | All other grass-like plants | |
| Rhynchospora nitens | short-beaked beaksedge | Cyperaceae | MA | Yes | Grass-like plants | All other grass-like plants | |
| Rhynchospora scirpoides | long-beaked beaksedge | Cyperaceae | CT MA RI | Yes | Grass-like plants | All other grass-like plants | |
| Rhynchospora torreyana | Torrey's beaksedge | Cyperaceae | MA RI | Yes | Grass-like plants | All other grass-like plants | |
| Ribes americanum | eastern black currant | Grossulariaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Ribes aureum | golden currant | Grossulariaceae | CT MA VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Ribes cynosbati | eastern prickly gooseberry | Grossulariaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Ribes glandulosum | skunk currant | Grossulariaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Ribes hirtellum | hairy-stemmed gooseberry | Grossulariaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Ribes lacustre | bristly swamp currant | Grossulariaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Ribes missouriense | Missouri gooseberry | Grossulariaceae | CT | Yes | Woody Plants | Broad-leaved woody plants | |
| Ribes nigrum | garden black currant | Grossulariaceae | CT MA ME NH VT | No | Woody Plants | Broad-leaved woody plants | |
| Ribes rotundifolium | Appalachian gooseberry | Grossulariaceae | CT MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Ribes rubrum | garden red currant | Grossulariaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Ribes triste | swamp red currant | Grossulariaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Ribes uva-crispa | European gooseberry | Grossulariaceae | CT MA ME NH VT | No | Woody Plants | Broad-leaved woody plants | |
| Ricinus communis | castor-bean | Euphorbiaceae | CT MA NH | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Robinia hispida | bristly locust | Fabaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Robinia pseudoacacia | black locust | Fabaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Robinia viscosa | clammy locust | Fabaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rorippa amphibia | great yellow-cress | Brassicaceae | MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Rorippa aquatica | lake yellow-cress | Brassicaceae | MA VT | Yes | Aquatic plants; All other flowering non-woody plants | Water plants with leaves and stems; Other herbaceous, flowering plants with alternate leaves | |
| Rorippa austriaca | Austrian yellow-cress | Brassicaceae | CT NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Rorippa globosa | globe yellow-cress | Brassicaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Rorippa palustris | common yellow-cress | Brassicaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Rorippa sessiliflora | stalkless yellow-cress | Brassicaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Rorippa sylvestris | creeping yellow-cress | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Rosa acicularis | bristly rose | Rosaceae | MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rosa arkansana | prairie rose | Rosaceae | MA ME | Yes | Woody Plants | Broad-leaved woody plants | |
| Rosa blanda | smooth rose | Rosaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rosa canina | dog rose | Rosaceae | CT MA ME RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Rosa carolina | Carolina rose | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rosa cinnamomea | cinnamon rose | Rosaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Rosa gallica | French rose | Rosaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Rosa glauca | red-leaved rose | Rosaceae | MA ME | No | Woody Plants | Broad-leaved woody plants | |
| Rosa luciae | memorial rose | Rosaceae | CT MA RI | No | Woody Plants | Broad-leaved woody plants | |
| Rosa micrantha | small-flowered sweet-briar rose | Rosaceae | CT MA ME RI | No | Woody Plants | Broad-leaved woody plants | |
| Rosa mollis | soft downy rose | Rosaceae | VT | No | Woody Plants | Broad-leaved woody plants | |
| Rosa multiflora | rambler rose | Rosaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Rosa nitida | shining rose | Rosaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rosa palustris | swamp rose | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rosa rubiginosa | sweet-briar rose | Rosaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Rosa rugosa | beach rose | Rosaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Rosa sempervirens | evergreen rose | Rosaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Rosa setigera | climbing rose | Rosaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rosa sherardii | Sherard's downy rose | Rosaceae | VT | No | Woody Plants | Broad-leaved woody plants | |
| Rosa spinosissima | Scotch rose | Rosaceae | CT MA ME NH VT | No | Woody Plants | Broad-leaved woody plants | |
| Rosa virginiana | Virginia rose | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rotala ramosior | toothcup | Lythraceae | CT MA NH RI | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Rubia tinctoria | madder | Rubiaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Rubus allegheniensis | common blackberry | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rubus arenicola | sandy field blackberry | Rosaceae | MA ME NH RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Rubus argutus | southern blackberry | Rosaceae | CT MA RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Rubus bifrons | twice-leaved blackberry | Rosaceae | MA RI | No | Woody Plants | Broad-leaved woody plants | |
| Rubus canadensis | smooth blackberry | Rosaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rubus chamaemorus | baked-apple-berry | Rosaceae | ME NH | Yes | |||
| Rubus cuneifolius | sand blackberry | Rosaceae | CT MA NH | Yes | Woody Plants | Broad-leaved woody plants | |
| Rubus dalibarda | dewdrop | Rosaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Rubus discolor | Himalayan blackberry | Rosaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Rubus elegantulus | showy blackberry | Rosaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rubus enslenii | Enslen's blackberry | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rubus flagellaris | northern blackberry, northern dewberry | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rubus frondosus | leafy-flowered blackberry | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rubus hispidus | bristly blackberry, swamp dewberry | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rubus idaeus | red raspberry | Rosaceae | CT MA ME NH RI VT | Yes and no (some introduced) | Woody Plants | Broad-leaved woody plants | |
| Rubus illecebrosus | strawberry raspberry | Rosaceae | CT MA ME | No | Woody Plants | Broad-leaved woody plants | |
| Rubus jaysmithii | Smith's blackberry | Rosaceae | MA NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rubus laciniatus | cut-leaved blackberry | Rosaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Rubus occidentalis | black raspberry | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rubus odoratus | flowering raspberry | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rubus parvifolius | Japanese raspberry | Rosaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Rubus pensilvanicus | Pennsylvania blackberry | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rubus phoenicolasius | wine raspberry | Rosaceae | CT MA RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Rubus pubescens | dwarf raspberry | Rosaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Rubus recurvicaulis | arching blackberry | Rosaceae | MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rubus semisetosus | northeastern blackberry | Rosaceae | CT MA ME NH RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Rubus setosus | setose blackberry | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rubus vermontanus | Vermont blackberry | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Rudbeckia bicolor | pine-woods coneflower | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Rudbeckia fulgida | showy coneflower | Asteraceae | CT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Rudbeckia hirta | black-eyed coneflower, black-eyed susan | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Rudbeckia laciniata | green-headed coneflower | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Rudbeckia subtomentosa | sweet coneflower | Asteraceae | CT MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Rudbeckia triloba | three-lobed coneflower | Asteraceae | CT MA VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Rumex acetosa | common dock | Polygonaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Rumex acetosella | common sheep sorrel, sheep dock | Polygonaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Rumex alpinus | alpine dock | Polygonaceae | ME VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Rumex altissimus | pale dock | Polygonaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Rumex britannica | greater water dock | Polygonaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Rumex crispus | curly dock | Polygonaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Rumex hastatulus | wild dock | Polygonaceae | MA ME | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Rumex longifolius | yard dock | Polygonaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Rumex maritimus | golden dock | Polygonaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Rumex obtusifolius | bitter dock | Polygonaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Rumex occidentalis | western dock | Polygonaceae | MA ME VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Rumex pallidus | seabeach dock | Polygonaceae | MA ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Rumex patientia | patience dock | Polygonaceae | CT MA ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Rumex persicarioides | American golden dock | Polygonaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Rumex pulcher | fiddle dock | Polygonaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Rumex triangulivalvis | white dock | Polygonaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Rumex verticillatus | swamp dock | Polygonaceae | CT MA RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Rumex violascens | violet dock | Polygonaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Ruppia maritima | beaked ditch-grass, widgeongrass | Ruppiaceae | CT MA ME NH RI | Yes | Aquatic plants | Water plants with leaves and stems | |
| Ruta graveolens | common rue | Rutaceae | CT RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sabatia angularis | common rose-gentian | Gentianaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Sabatia campanulata | slender rose-gentian | Gentianaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Sabatia campestris | western rose-gentian | Gentianaceae | CT ME | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Sabatia dodecandra | perennial rose-gentian | Gentianaceae | CT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Sabatia kennedyana | Plymouth rose-gentian | Gentianaceae | MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Sabatia stellaris | annual rose-gentian | Gentianaceae | CT MA RI | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Sacciolepis striata | American cup-scale | Poaceae | MA | Yes | Grass-like plants | True grasses | |
| Sagina decumbens | trailing pearlwort | Caryophyllaceae | CT MA VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Sagina japonica | Japanese pearlwort | Caryophyllaceae | CT MA RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Sagina maxima | sticky-stemmed pearlwort | Caryophyllaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Sagina nodosa | knotted pearlwort | Caryophyllaceae | MA ME NH | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Sagina procumbens | bird's-eye pearlwort | Caryophyllaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Sagittaria cuneata | northern arrowhead | Alismataceae | CT MA ME NH VT | Yes | Orchids and related plants; Aquatic plants | Irises, lilies, and other "monocots"; Water plants with leaves and stems | |
| Sagittaria engelmanniana | Engelmann's arrowhead | Alismataceae | CT MA RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Sagittaria filiformis | narrow-leaved arrowhead | Alismataceae | CT MA ME RI | Yes | Aquatic plants | Water plants with leaves and stems | |
| Sagittaria graminea | grass-leaved arrowhead | Alismataceae | CT MA ME NH RI VT | Yes | Orchids and related plants; Aquatic plants | Irises, lilies, and other "monocots"; Water plants with leaves and stems | |
| Sagittaria latifolia | common arrowhead | Alismataceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Sagittaria montevidensis | spongy-leaved arrowhead | Alismataceae | CT MA ME NH | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Sagittaria rigida | sessile-fruited arrowhead | Alismataceae | CT MA ME NH RI VT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Sagittaria subulata | awl-leaved arrowhead | Alismataceae | CT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Sagittaria teres | quill-leaved arrowhead | Alismataceae | CT MA NH RI | Yes | Orchids and related plants; Aquatic plants | Irises, lilies, and other "monocots"; Water plants with leaves and stems | |
| Salicornia ambigua | perennial glasswort | Amaranthaceae | CT MA NH RI | Yes | All other flowering non-woody plants; Woody Plants | Other herbaceous, flowering plants with opposite, whorled or no leaves; Broad-leaved woody plants | |
| Salicornia bigelovii | dwarf glasswort | Amaranthaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Salicornia depressa | common glasswort | Amaranthaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Salicornia maritima | sea glasswort | Amaranthaceae | ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Salix alba | white willow | Salicaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Salix amygdaloides | peach-leaved willow | Salicaceae | VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Salix arctophila | northern willow | Salicaceae | ME | Yes | Woody Plants | Broad-leaved woody plants | |
| Salix argyrocarpa | Labrador willow | Salicaceae | ME NH | Yes | Woody Plants | Broad-leaved woody plants | |
| Salix aurita | eared willow | Salicaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Salix bebbiana | long-beaked willow | Salicaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Salix candida | sage willow | Salicaceae | CT MA ME VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Salix caprea | goat willow | Salicaceae | CT RI | No | Woody Plants | Broad-leaved woody plants | |
| Salix cinerea | gray willow | Salicaceae | CT MA ME RI | No | Woody Plants | Broad-leaved woody plants | |
| Salix discolor | pussy willow | Salicaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Salix elaeagnos | hoary willow | Salicaceae | CT MA ME | No | Woody Plants | Broad-leaved woody plants | |
| Salix eriocephala | heart-leaved willow | Salicaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Salix exigua | sandbar willow | Salicaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Salix herbacea | snow-bed willow | Salicaceae | ME NH | Yes | Woody Plants | Broad-leaved woody plants | |
| Salix humilis | prairie willow | Salicaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Salix lucida | shining willow | Salicaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Salix myricoides | bayberry willow | Salicaceae | ME | Yes | Woody Plants | Broad-leaved woody plants | |
| Salix nigra | black willow | Salicaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Salix occidentalis | dwarf prairie willow | Salicaceae | CT MA ME NH RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Salix pedicellaris | bog willow | Salicaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Salix pellita | satiny willow | Salicaceae | ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Salix pentandra | laurel willow | Salicaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Salix petiolaris | meadow willow | Salicaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Salix planifolia | tea-leaved willow | Salicaceae | ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Salix purpurea | basket willow | Salicaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Salix pyrifolia | balsam willow | Salicaceae | ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Salix sericea | silky willow | Salicaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Salix serissima | autumn willow | Salicaceae | CT MA VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Salix uva-ursi | bearberry willow | Salicaceae | ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Salix viminalis | osier willow | Salicaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Salpiglossis sinuata | paintedtongue | Solanaceae | CT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Salsola collina | slender saltwort | Amaranthaceae | MA NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Salsola kali | saltwort | Amaranthaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Salsola tragus | prickly saltwort | Amaranthaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Salvia azurea | azure-blue sage | Lamiaceae | CT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Salvia lyrata | lyre-leaved sage | Lamiaceae | CT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Salvia nemorosa | woodland sage | Lamiaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Salvia officinalis | West Indian sage | Lamiaceae | CT ME RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Salvia pratensis | meadow sage | Lamiaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Salvia sclarea | cleareye sage | Lamiaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Salvia splendens | scarlet sage | Lamiaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Salvia tiliifolia | linden-leaved sage | Lamiaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Salvia verticillata | whorled sage | Lamiaceae | CT MA VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Salvinia minima | common watermoss | Salviniaceae | MA | No | Aquatic plants; Ferns | Water plants with leaves and stems; True ferns and moonworts | |
| Sambucus nigra | black elderberry | Adoxaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Sambucus racemosa | red elderberry | Adoxaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Samolus valerandi | seaside brookweed | Theophrastaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sanguinaria canadensis | blood-root | Papaveraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Sanguisorba canadensis | Canada burnet | Rosaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sanguisorba minor | salad burnet | Rosaceae | CT MA ME RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sanguisorba officinalis | great burnet | Rosaceae | ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sanicula canadensis | Canada sanicle | Apiaceae | CT MA NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sanicula marilandica | Maryland sanicle | Apiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sanicula odorata | clustered sanicle | Apiaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sanicula trifoliata | large-fruited sanicle | Apiaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Santolina chamaecyparissus | lavender-cotton | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Saponaria ocymoides | rock soapwort | Caryophyllaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Saponaria officinalis | common soapwort | Caryophyllaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Saponaria pumilio | pygmy soapwort | Caryophyllaceae | NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Sarracenia purpurea | purple pitcherplant | Sarraceniaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Sassafras albidum | sassafras | Lauraceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Satureja hortensis | summer savory | Lamiaceae | CT MA ME VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Saururus cernuus | lizard's-tail | Saururaceae | CT MA RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Saxifraga aizoides | yellow mountain saxifrage | Saxifragaceae | VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Saxifraga cernua | nodding saxifrage | Saxifragaceae | NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Saxifraga oppositifolia | purple mountain saxifrage | Saxifragaceae | VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Saxifraga paniculata | white mountain saxifrage | Saxifragaceae | ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Saxifraga rivularis | alpine-brook saxifrage | Saxifragaceae | NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Scabiosa columbaria | dove pincushions | Caprifoliaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Scabiosa ochroleuca | cream pincushions | Caprifoliaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Scandix pecten-veneris | shepherd's-needle | Apiaceae | MA RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Schedonorus arundinaceus | tall rye grass | Poaceae | CT MA ME VT | No | Grass-like plants | True grasses | |
| Schedonorus giganteus | giant rye grass | Poaceae | CT | No | Grass-like plants | True grasses | |
| Schedonorus pratensis | meadow rye grass | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Schenkia spicata | spiked centaury | Gentianaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Scheuchzeria palustris | pod-grass | Scheuchzeriaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Schizachne purpurascens | false melic grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Schizachyrium littorale | dune bluestem | Poaceae | CT | Yes | Grass-like plants | True grasses | |
| Schizachyrium scoparium | little bluestem | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Schkuhria pinnata | feathery false threadleaf | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Schoenoplectus acutus | hard-stemmed bulrush | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Schoenoplectus americanus | chair-maker's bulrush | Cyperaceae | CT MA RI | Yes | Grass-like plants | All other grass-like plants | |
| Schoenoplectus etuberculatus | Canby's bulrush | Cyperaceae | RI | Yes | Grass-like plants | All other grass-like plants | |
| Schoenoplectus hallii | Hall's bulrush | Cyperaceae | MA | Yes | Grass-like plants | All other grass-like plants | |
| Schoenoplectus heterochaetus | slender bulrush | Cyperaceae | MA VT | Yes | Grass-like plants | All other grass-like plants | |
| Schoenoplectus pungens | three-square bulrush | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Schoenoplectus purshianus | weak-stalked bulrush | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Schoenoplectus smithii | Smith's bulrush | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Schoenoplectus subterminalis | water bulrush | Cyperaceae | CT MA ME NH RI VT | Yes | Aquatic plants; Grass-like plants | Water plants with leaves and stems; All other grass-like plants | |
| Schoenoplectus tabernaemontani | soft-stemmed bulrush | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Schoenoplectus torreyi | Torrey's bulrush | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Schwalbea americana | chaff-seed | Orobanchaceae | CT MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Scirpus ancistrochaetus | northeastern bulrush | Cyperaceae | MA NH VT | Yes | Grass-like plants | All other grass-like plants | |
| Scirpus atrocinctus | black-girdled woolsedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Scirpus atrovirens | dark-green bulrush | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Scirpus cyperinus | common woolsedge, woolgrass | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Scirpus expansus | wood bulrush | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Scirpus georgianus | Georgia bulrush | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Scirpus hattorianus | mosquito bulrush | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Scirpus longii | Long's woolsedge | Cyperaceae | CT MA ME NH RI | Yes | Grass-like plants | All other grass-like plants | |
| Scirpus microcarpus | barber-pole bulrush | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Scirpus pedicellatus | stalked woolsedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Scirpus pendulus | rufous bulrush | Cyperaceae | CT MA ME NH VT | Yes | Grass-like plants | All other grass-like plants | |
| Scirpus polyphyllus | leafy bulrush | Cyperaceae | CT MA NH VT | Yes | Grass-like plants | All other grass-like plants | |
| Scleranthus annuus | annual knawel, German knotgrass | Caryophyllaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Scleranthus perennis | perennial knawel | Caryophyllaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Scleria pauciflora | few-flowered nutsedge | Cyperaceae | CT MA NH RI | Yes | Grass-like plants | All other grass-like plants | |
| Scleria reticularis | netted nutsedge | Cyperaceae | CT MA NH RI | Yes | Grass-like plants | All other grass-like plants | |
| Scleria triglomerata | whip nutsedge | Cyperaceae | CT MA RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Scleria verticillata | low nutsedge | Cyperaceae | CT | Yes | Grass-like plants | All other grass-like plants | |
| Sclerolepis uniflora | sclerolepis | Asteraceae | MA NH RI | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Scorpiurus muricatus | prickly scorpion's-tail | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Scorzoneroides autumnalis | fall-dandelion | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Scrophularia lanceolata | lance-leaved figwort | Scrophulariaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Scrophularia marilandica | eastern figwort | Scrophulariaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Scrophularia nodosa | woodland figwort | Scrophulariaceae | MA ME RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Scutellaria altissima | tall skullcap | Lamiaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Scutellaria galericulata | hooded skullcap | Lamiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Scutellaria integrifolia | entire-leaved skullcap | Lamiaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Scutellaria lateriflora | mad dog skullcap | Lamiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Scutellaria parvula | little skullcap | Lamiaceae | CT MA ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Secale cereale | cultivated rye | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Securigera varia | purple crown-vetch | Fabaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sedum acre | moss stonecrop | Crassulaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sedum album | white stonecrop | Crassulaceae | ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sedum hispanicum | Spanish stonecrop | Crassulaceae | MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sedum ochroleucum | European stonecrop | Crassulaceae | ME | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sedum reflexum | rock stonecrop | Crassulaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sedum sarmentosum | stringy stonecrop | Crassulaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Sedum sexangulare | six-angled stonecrop | Crassulaceae | CT MA NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sedum ternatum | woodland stonecrop | Crassulaceae | CT MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Selaginella apoda | meadow spikemoss | Selaginellaceae | CT MA ME NH RI VT | Yes | Ferns | Clubmosses and relatives, plus quillworts | |
| Selaginella eclipes | hidden spikemoss | Selaginellaceae | CT MA | Yes | Ferns | Clubmosses and relatives, plus quillworts | |
| Selaginella rupestris | ledge spikemoss | Selaginellaceae | CT MA ME NH RI VT | Yes | Ferns | Clubmosses and relatives, plus quillworts | |
| Selaginella selaginoides | northern spikemoss | Selaginellaceae | ME | Yes | Ferns | Clubmosses and relatives, plus quillworts | |
| Selinum carvifolia | little-leaved-angelica | Apiaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sempervivum tectorum | hens-and-chickens | Crassulaceae | CT MA ME NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Senecio spartioides | broom-like ragwort | Asteraceae | MA | Yes | Woody Plants; All other flowering non-woody plants | Broad-leaved woody plants; Daisies, goldenrods, and other Aster family plants | |
| Senecio suaveolens | false Indian-plantain | Asteraceae | CT MA RI | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Senecio sylvaticus | woodland ragwort | Asteraceae | ME | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Senecio viscosus | sticky ragwort | Asteraceae | CT MA ME NH RI VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Senecio vulgaris | common ragwort | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Senna hebecarpa | northern wild senna | Fabaceae | CT MA NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Senna obtusifolia | sickle-pod wild senna | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Sericocarpus asteroides | toothed white-topped-aster | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Sericocarpus linifolius | narrow-leaved white-topped-aster | Asteraceae | CT MA NH RI | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Sesamum orientale | sesame | Pedaliaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Sesbania herbacea | tall river-hemp | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Sesuvium maritimum | annual sea-purslane | Aizoaceae | RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Setaria faberi | Chinese foxtail | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Setaria italica | millet foxtail | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Setaria parviflora | knotroot foxtail | Poaceae | CT MA RI | Yes | Grass-like plants | True grasses | |
| Setaria pumila | yellow foxtail | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Setaria verticillata | hooked foxtail | Poaceae | CT MA ME RI VT | No | Grass-like plants | True grasses | |
| Setaria viridis | green foxtail | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Shepherdia canadensis | Canada buffalo-berry | Elaeagnaceae | ME VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Sherardia arvensis | blue field-madder | Rubiaceae | CT MA ME RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Shortia galacifolia | Oconee-bells | Diapensiaceae | CT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Sibbaldia procumbens | sibbaldia | Rosaceae | NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Sibbaldiopsis tridentata | three-toothed-cinquefoil | Rosaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sicyos angulatus | one-seeded burr-cucumber | Cucurbitaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sida hermaphrodita | Virginia fanpetals | Malvaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Sida spinosa | prickly fanpetals | Malvaceae | CT MA ME | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Sideritis montana | mountain ironwort | Lamiaceae | CT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Sigesbeckia orientalis | common St. Paul's-wort | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Silene acaulis | moss campion | Caryophyllaceae | ME NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Silene antirrhina | sleepy campion | Caryophyllaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Silene caroliniana | wild campion | Caryophyllaceae | CT MA NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Silene conica | striate campion | Caryophyllaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Silene csereii | Balkan campion | Caryophyllaceae | MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Silene dichotoma | forked campion | Caryophyllaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Silene dioica | red campion | Caryophyllaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Silene gallica | windmill campion | Caryophyllaceae | CT MA ME NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Silene latifolia | white campion | Caryophyllaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Silene nivea | snowy campion | Caryophyllaceae | MA ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Silene noctiflora | night-flowering campion | Caryophyllaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Silene nutans | Eurasian campion | Caryophyllaceae | ME | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Silene pendula | nodding campion | Caryophyllaceae | ME | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Silene stellata | starry campion | Caryophyllaceae | CT RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Silene vulgaris | bladder campion | Caryophyllaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Silphium perfoliatum | cup-plant rosinweed | Asteraceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Silybum marianum | blessed milk-thistle | Asteraceae | CT MA NH | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Sinapis alba | white charlock | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sinapis arvensis | corn charlock | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sisymbrium altissimum | tumbling hedge-mustard | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sisymbrium irio | London hedge-mustard | Brassicaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sisymbrium loeselii | tall hedge-mustard | Brassicaceae | CT MA NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sisymbrium officinale | common hedge-mustard | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sisymbrium orientale | Indian hedge-mustard | Brassicaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Sisyrinchium albidum | white blue-eyed-grass | Iridaceae | ME | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Sisyrinchium angustifolium | narrow-leaved blue-eyed-grass | Iridaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Sisyrinchium atlanticum | eastern blue-eyed-grass | Iridaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Sisyrinchium fuscatum | coastal plain blue-eyed-grass | Iridaceae | MA RI | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Sisyrinchium montanum | strict blue-eyed-grass | Iridaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Sisyrinchium mucronatum | needle-tipped blue-eyed-grass | Iridaceae | CT MA ME NH VT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Sium suave | water-parsnip | Apiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants; Aquatic plants | Other herbaceous, flowering plants with alternate leaves; Water plants with leaves and stems | |
| Smilax glauca | glaucous-leaved greenbriar | Smilacaceae | CT MA RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Smilax herbacea | carrion-flower | Smilacaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Smilax hispida | bristly greenbrier | Smilacaceae | CT | Woody Plants | Broad-leaved woody plants | ||
| Smilax rotundifolia | carrion-flower, roundleaf greenbrier | Smilacaceae | CT MA ME NH RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Solanum carolinense | Carolina nightshade | Solanaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Solanum citrullifolium | watermelon nightshade | Solanaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Solanum dulcamara | climbing nightshade | Solanaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Solanum lycopersicon | garden tomato | Solanaceae | CT MA NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Solanum melongena | eggplant | Solanaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Solanum nigrum | European black nightshade | Solanaceae | MA ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Solanum physalifolium | ground-cherry nightshade | Solanaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Solanum pseudocapsicum | Jerusalem-cherry nightshade | Solanaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Solanum ptycanthum | eastern black nightshade | Solanaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Solanum rostratum | horned nightshade | Solanaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Solanum sisymbriifolium | sticky nightshade | Solanaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Solanum triflorum | cut-leaved nightshade | Solanaceae | CT MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Solanum tuberosum | Irish potato | Solanaceae | CT MA ME NH RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Solanum villosum | hairy nightshade | Solanaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Solidago aestivalis | swamp wrinkle-leaved goldenrod | Asteraceae | CT MA ME NH RI | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Solidago altissima | tall goldenrod | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Solidago arguta | forest goldenrod | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Solidago bicolor | white goldenrod | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Solidago caesia | axillary goldenrod, blue-stem goldenrod | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Solidago canadensis | Canada goldenrod | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Solidago erecta | slender goldenrod | Asteraceae | CT MA RI | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Solidago flexicaulis | zig-zag goldenrod | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Solidago gigantea | smooth goldenrod | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Solidago hispida | hairy goldenrod | Asteraceae | CT MA ME NH RI VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Solidago juncea | early goldenrod | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Solidago latissimifolia | Elliott's goldenrod | Asteraceae | CT MA RI | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Solidago leiocarpa | Cutler's goldenrod | Asteraceae | ME NH VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Solidago macrophylla | large-leaved goldenrod | Asteraceae | MA ME NH VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Solidago nemoralis | gray goldenrod | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Solidago odora | licorice goldenrod | Asteraceae | CT MA NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Solidago patula | rough-leaved goldenrod | Asteraceae | CT MA NH VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Solidago puberula | downy goldenrod | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Solidago rugosa | common wrinkle-leaved goldenrod | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Solidago sempervirens | seaside goldenrod | Asteraceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Solidago simplex | Rand's goldenrod | Asteraceae | MA ME NH VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Solidago speciosa | showy goldenrod | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Solidago squarrosa | squarrose goldenrod | Asteraceae | CT MA ME NH VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Solidago uliginosa | bog goldenrod | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Solidago ulmifolia | elm-leaved goldenrod | Asteraceae | CT MA ME RI VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Sonchus arvensis | field sow-thistle | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Sonchus asper | spiny-leaved sow-thistle | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Sonchus oleraceus | common sow-thistle | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Sorbaria sorbifolia | false spiraea | Rosaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Sorbus alnifolia | Korean mountain-ash | Rosaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Sorbus americana | American mountain-ash | Rosaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Sorbus aucuparia | European mountain-ash | Rosaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Sorbus decora | showy mountain-ash | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Sorbus hybrida | oak-leaved mountain-ash | Rosaceae | ME NH | No | Woody Plants | Broad-leaved woody plants | |
| Sorghastrum nutans | Indian grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Sorghum bicolor | sorghum | Poaceae | CT MA RI VT | No | Grass-like plants | True grasses | |
| Sorghum halepense | Johnson grass | Poaceae | CT MA VT | No | Grass-like plants | True grasses | |
| Sparganium americanum | American bur-reed | Typhaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Sparganium androcladum | branched bur-reed | Typhaceae | CT MA ME NH RI VT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Sparganium angustifolium | narrow-leaved bur-reed | Typhaceae | CT MA ME NH VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Sparganium emersum | simple-stemmed bur-reed | Typhaceae | CT MA ME NH VT | No | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Sparganium eurycarpum | great bur-reed | Typhaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Sparganium fluctuans | floating bur-reed | Typhaceae | CT MA ME NH VT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Sparganium natans | arctic bur-reed | Typhaceae | CT MA ME NH VT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Spartina alterniflora | smooth cordgrass | Poaceae | CT MA ME NH RI | Yes | Grass-like plants | True grasses | |
| Spartina cynosuroides | big cordgrass | Poaceae | CT MA RI | Yes | Grass-like plants | True grasses | |
| Spartina patens | saltmarsh hay, saltmeadow cordgrass | Poaceae | CT MA ME NH RI | Yes | Grass-like plants | True grasses | |
| Spartina pectinata | prairie cordgrass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Spergula arvensis | corn spurry | Caryophyllaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Spergula morisonii | Morison's spurry | Caryophyllaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Spergula pentandra | five-stamened spurry | Caryophyllaceae | CT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Spergularia canadensis | Canada sand-spurry | Caryophyllaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Spergularia marina | saltmarsh sand-spurry | Caryophyllaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Spergularia rubra | red sand-spurry | Caryophyllaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Sphaeralcea mendocina | Mendoza globe-mallow | Malvaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Sphenopholis intermedia | slender wedgescale | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Sphenopholis nitida | shiny wedgescale | Poaceae | CT MA RI VT | Yes | Grass-like plants | True grasses | |
| Sphenopholis obtusata | prairie wedgescale | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Sphenopholis pensylvanica | swamp wedgescale | Poaceae | CT MA RI | Yes | Grass-like plants | True grasses | |
| Spinacea oleracea | spinach | Amaranthaceae | CT MA ME NH RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Spinulum annotinum | bristly clubmoss, common interrupted-clubmoss | Lycopodiaceae | CT MA ME NH RI VT | Yes | Ferns | Clubmosses and relatives, plus quillworts | |
| Spinulum canadense | northern interrupted-clubmoss | Lycopodiaceae | ME NH VT | Yes | Ferns | Clubmosses and relatives, plus quillworts | |
| Spiraea alba | white meadowsweet | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Spiraea chamaedryfolia | germander meadowsweet | Rosaceae | CT | No | Woody Plants | Broad-leaved woody plants | |
| Spiraea japonica | Japanese meadowsweet | Rosaceae | CT MA ME NH RI | No | Woody Plants | Broad-leaved woody plants | |
| Spiraea prunifolia | bridalwreath meadowsweet | Rosaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Spiraea thunbergii | Thunberg's meadowsweet | Rosaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Spiraea tomentosa | rosy meadowsweet, steeplebush | Rosaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Spiranthes casei | Case's ladies'-tresses | Orchidaceae | ME NH VT | Yes | Orchids and related plants | Orchids | |
| Spiranthes cernua | nodding ladies'-tresses | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Spiranthes lacera | slender ladies'-tresses | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Spiranthes lucida | shining ladies'-tresses | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Spiranthes ochroleuca | yellow ladies'-tresses | Orchidaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Orchids | |
| Spiranthes romanzoffiana | hooded ladies'-tresses | Orchidaceae | CT MA ME NH VT | Yes | Orchids and related plants | Orchids | |
| Spiranthes tuberosa | little ladies'-tresses | Orchidaceae | CT MA RI | Yes | Orchids and related plants | Orchids | |
| Spiranthes vernalis | spring ladies'-tresses | Orchidaceae | CT MA NH RI | Yes | Orchids and related plants | Orchids | |
| Spirodela polyrrhiza | common duck-meal | Araceae | CT MA ME NH RI VT | Yes | Aquatic plants | Tiny water plants with no true stem | |
| Sporobolus clandestinus | hidden dropseed | Poaceae | CT MA | Yes | Grass-like plants | True grasses | |
| Sporobolus compositus | rough dropseed | Poaceae | CT MA ME RI VT | Yes | Grass-like plants | True grasses | |
| Sporobolus contractus | narrow-spiked dropseed | Poaceae | ME | Yes | Grass-like plants | True grasses | |
| Sporobolus cryptandrus | sand dropseed | Poaceae | CT MA ME NH VT | Yes | Grass-like plants | True grasses | |
| Sporobolus heterolepis | prairie dropseed | Poaceae | CT MA | Yes | Grass-like plants | True grasses | |
| Sporobolus neglectus | small dropseed | Poaceae | CT MA ME NH VT | Yes | Grass-like plants | True grasses | |
| Sporobolus vaginiflorus | poverty dropseed | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Stachys annua | annual hedge-nettle | Lamiaceae | MA ME RI | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Stachys arvensis | field hedge-nettle | Lamiaceae | MA ME | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Stachys byzantina | woolly hedge-nettle | Lamiaceae | CT RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Stachys clingmanii | Clingman's hedge-nettle | Lamiaceae | VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Stachys germanica | German hedge-nettle | Lamiaceae | RI | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Stachys hispida | hispid hedge-nettle | Lamiaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Stachys hyssopifolia | hyssop-leaved hedge-nettle | Lamiaceae | CT MA ME NH RI | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Stachys palustris | marsh hedge-nettle | Lamiaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Stachys pilosa | hairy hedge-nettle | Lamiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Staphylea trifolia | American bladdernut | Staphyleaceae | CT MA NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Stellaria alsine | bog stitchwort | Caryophyllaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Stellaria borealis | boreal starwort, boreal stitchwort | Caryophyllaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Stellaria corei | Tennessee stitchwort | Caryophyllaceae | CT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Stellaria graminea | grass-leaved starwort, grass-leaved stitchwort | Caryophyllaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Stellaria holostea | greater stitchwort | Caryophyllaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Stellaria humifusa | saltmarsh stitchwort | Caryophyllaceae | ME | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Stellaria longifolia | long-leaved stitchwort | Caryophyllaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Stellaria media | common starwort, common stitchwort | Caryophyllaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Stenanthium gramineum | eastern featherbells | Melanthiaceae | CT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Streptopus amplexifolius | clasping-leaved twistedstalk | Liliaceae | CT MA ME NH VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Streptopus lanceolatus | lance-leaved twistedstalk | Liliaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Strophostyles helvola | annual woolly bean | Fabaceae | CT MA ME RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Strophostyles leiosperma | small-flowered woolly bean | Fabaceae | CT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Strophostyles umbellata | perennial woolly bean | Fabaceae | RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Stuckenia filiformis | thread-leaved false pondweed | Potamogetonaceae | ME NH VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Stuckenia pectinata | Sago false pondweed | Potamogetonaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Suaeda calceoliformis | American sea-blite | Amaranthaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Suaeda linearis | annual sea-blite | Amaranthaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Suaeda maritima | herbaceous sea-blite | Amaranthaceae | CT MA ME NH RI | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Subularia aquatica | American water-awlwort | Brassicaceae | ME NH VT | Yes | All other flowering non-woody plants; Aquatic plants | Other herbaceous, flowering plants with alternate leaves; Water plants with leaves and stems | |
| Succisa pratensis | devil's-bit | Caprifoliaceae | MA RI | No | |||
| Succisella inflexa | southern succisella | Caprifoliaceae | CT MA | No | |||
| Swida alternifolia | alternate-leaved dogwood, pagoda dogwood | Cornaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Swida amomum | silky dogwood | Cornaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Swida racemosa | gray dogwood | Cornaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Swida rugosa | round-leaved dogwood | Cornaceae | Yes | Woody Plants | Broad-leaved woody plants | ||
| Swida sanguinea | blood-twig dogwood | Cornaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Swida sericea | red-osier dogwood | Cornaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Symphoricarpos albus | common snowberry | Caprifoliaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Symphoricarpos orbiculatus | red snowberry | Caprifoliaceae | CT MA RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Symphyotrichum anticostense | Anticosti American-aster | Asteraceae | ME | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Symphyotrichum boreale | rush American-aster | Asteraceae | ME NH VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Symphyotrichum ciliatum | rayless annual American-aster | Asteraceae | VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Symphyotrichum ciliolatum | Lindley's American-aster | Asteraceae | MA ME VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Symphyotrichum concolor | eastern silver American-aster | Asteraceae | MA RI | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Symphyotrichum cordifolium | heart-leaved American-aster | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Symphyotrichum dumosum | bushy American-aster | Asteraceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Symphyotrichum ericoides | heath American-aster | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Symphyotrichum frondosum | leafy annual American-aster | Asteraceae | ME | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Symphyotrichum laeve | smooth American-aster | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Symphyotrichum lanceolatum | lance-leaved American-aster | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Symphyotrichum lateriflorum | calico American-aster | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Symphyotrichum lowrieanum | Lowrie's American-aster | Asteraceae | CT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Symphyotrichum novae-angliae | New England American-aster | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Symphyotrichum novi-belgii | New York American-aster | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Symphyotrichum ontarionis | Ontario American-aster | Asteraceae | VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Symphyotrichum patens | late purple American-aster | Asteraceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Symphyotrichum pilosum | awl American-aster | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Symphyotrichum praealtum | willow-leaved American-aster | Asteraceae | CT MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Symphyotrichum prenanthoides | crooked-stemmed American-aster | Asteraceae | CT MA VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Symphyotrichum puniceum | purple-stemmed American-aster | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Symphyotrichum racemosum | small white American-aster | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Symphyotrichum subulatum | annual saltmarsh American-aster | Asteraceae | CT MA ME NH RI | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Symphyotrichum tenuifolium | perennial saltmarsh American-aster | Asteraceae | CT MA NH RI | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Symphyotrichum tradescantii | Tradescant's American-aster | Asteraceae | MA ME NH VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Symphyotrichum undulatum | wavy-leaved American-aster | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Symphyotrichum urophyllum | arrow-leaved American-aster | Asteraceae | VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Symphytum asperum | prickly comfrey | Boraginaceae | CT MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Symphytum officinale | common comfrey | Boraginaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Symphytum tuberosum | tuberous comfrey | Boraginaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Symplocarpus foetidus | skunk-cabbage | Araceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Symplocos paniculata | Asiatic sweetleaf, sapphire-berry | Symplocaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Syringa josikaea | Hungarian lilac | Oleaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Syringa reticulata | Japanese tree lilac | Oleaceae | MA NH VT | No | Woody Plants | Broad-leaved woody plants | |
| Syringa villosa | late lilac | Oleaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Syringa vulgaris | common lilac | Oleaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Taeniatherum caput-medusae | Medusa-head | Poaceae | CT | No | Grass-like plants | True grasses | |
| Taenidia integerrima | yellow-pimpernel | Apiaceae | CT RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Tagetes erecta | Aztec marigold | Asteraceae | CT MA VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Tagetes minuta | miniature marigold | Asteraceae | CT MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Tagetes patula | French marigold | Asteraceae | VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Tamarix parviflora | small-flowered tamarisk | Tamaricaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Tanacetum bipinnatum | eastern tansy | Asteraceae | ME | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Tanacetum parthenium | feverfew tansy | Asteraceae | CT MA ME NH RI VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Tanacetum vulgare | common tansy | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Taraxacum laevigatum | red-seeded dandelion | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Taraxacum latilobum | large-lobed dandelion | Asteraceae | MA ME | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Taraxacum officinale | common dandelion | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Taraxacum palustre | marsh dandelion | Asteraceae | CT VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Tarenaya hassleriana | giant spider-flower | Cleomaceae | CT MA RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Taxus baccata | English yew | Taxaceae | MA | No | Woody Plants | Needle-leaved woody plants | |
| Taxus canadensis | American yew | Taxaceae | CT MA ME NH RI VT | Yes | Woody Plants | Needle-leaved woody plants | |
| Taxus cuspidata | Japanese yew | Taxaceae | CT MA VT | No | Woody Plants | Needle-leaved woody plants | |
| Teesdalia nudicaulis | common shepherd's-cress | Brassicaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Tephrosia virginiana | wild goat's-rue | Fabaceae | CT MA NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Tetragonia tetragonioides | New Zealand-spinach | Aizoaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Teucrium botrys | cut-leaved germander | Lamiaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Teucrium canadense | American germander | Lamiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Teucrium scorodonia | woodland germander | Lamiaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Thalictrum dasycarpum | purple meadow-rue | Ranunculaceae | CT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Thalictrum dioicum | early meadow-rue | Ranunculaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Thalictrum pubescens | tall meadow-rue | Ranunculaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Thalictrum revolutum | waxy-leaved meadow-rue | Ranunculaceae | CT MA NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Thalictrum thalictroides | anemone meadow-rue, rue anemone | Ranunculaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Thalictrum venulosum | veiny-leaved meadow-rue | Ranunculaceae | ME VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Thaspium trifoliolatum | purple meadow-parsnip | Apiaceae | RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Thelypteris palustris | marsh fern | Thelypteridaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Thermopsis villosa | Blue Ridge false lupine | Fabaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Thinopyrum pycnanthum | tick quack grass | Poaceae | MA ME RI | No | Grass-like plants | True grasses | |
| Thladiantha dubia | Manchu tuber gourd | Cucurbitaceae | MA NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Thlaspi arvense | field penny-cress | Brassicaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Thuja occidentalis | northern white-cedar | Cupressaceae | CT MA ME NH RI VT | Yes and no (some introduced) | Woody Plants | Needle-leaved woody plants | |
| Thymophylla tenuiloba | Dahlburg-daisy | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Thymus pulegioides | lemon thyme | Lamiaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Thymus vulgaris | garden thyme | Lamiaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Tiarella cordifolia | foam-flower | Saxifragaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Tilia americana | American linden | Malvaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Tilia cordata | little-leaf basswood, small-leaved linden | Malvaceae | CT MA ME RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Tilia petiolaris | pendent silver basswood, pendent silver linden | Malvaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Tilia platyphyllos | large-leaved basswood, large-leaved linden | Malvaceae | ME | No | Woody Plants | Broad-leaved woody plants | |
| Tipularia discolor | cranefly orchid | Orchidaceae | MA | Yes | Orchids and related plants | Orchids | |
| Torilis japonica | erect hedge-parsley | Apiaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Torilis leptophylla | bristle-fruited hedge-parsley | Apiaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Torreyochloa pallida | pale false manna grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants; Aquatic plants | True grasses; Water plants with leaves and stems | |
| Toxicodendron radicans | poison-ivy | Anacardiaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Toxicodendron rydbergii | western poison-ivy | Anacardiaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Toxicodendron vernix | poison-sumac | Anacardiaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Tradescantia bracteata | long-bracted spiderwort | Commelinaceae | MA VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Tradescantia ohiensis | smooth spiderwort | Commelinaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Tradescantia virginiana | Virginia spiderwort | Commelinaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Tragopogon dubius | fistulous goat's beard, yellow salsify | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Tragopogon porrifolius | purple goat's beard | Asteraceae | CT MA ME NH VT | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Tragopogon pratensis | jack-go-to-bed-at-noon, meadow goat's beard | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Tragus berteronianus | spike burgrass | Poaceae | MA ME | No | Grass-like plants | True grasses | |
| Tragus racemosus | stalked burgrass | Poaceae | ME | No | Grass-like plants | True grasses | |
| Trapa natans | water-chestnut | Lythraceae | CT MA NH VT | Aquatic plants | Water plants with leaves and stems | ||
| Triadenum fraseri | Fraser's marsh-St. John's-wort | Hypericaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Triadenum virginicum | Virginia marsh-St. John's-wort | Hypericaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Triantha glutinosa | sticky false asphodel | Tofieldiaceae | ME NH VT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Tribulus terrestris | puncture-vine | Zygophyllaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Trichomanes intricatum | Appalachian bristle fern | Hymenophyllaceae | CT MA NH VT | Yes | Ferns | True ferns and moonworts | |
| Trichophorum alpinum | alpine bulrush, alpine clubsedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Trichophorum cespitosum | tufted clubsedge | Cyperaceae | ME NH VT | Yes | Grass-like plants | All other grass-like plants | |
| Trichophorum clintonii | Clinton's bulrush, Clinton's clubsedge | Cyperaceae | ME | Yes | Grass-like plants | All other grass-like plants | |
| Trichophorum planifolium | bashful bulrush, bashful clubsedge | Cyperaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Trichostema brachiatum | pennyroyal bluecurls | Lamiaceae | CT MA VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Trichostema dichotomum | forked bluecurls | Lamiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Trichostema setaceum | narrow-leaved bluecurls | Lamiaceae | CT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Tricyrtis hirta | hairy toad-lily | Liliaceae | MA | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Tridens flavus | purpletop tridens | Poaceae | CT MA NH RI VT | Yes | Grass-like plants | True grasses | |
| Trifolium arvense | rabbit-foot clover | Fabaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Trifolium aureum | palmate hop clover | Fabaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Trifolium campestre | pinnate hop clover | Fabaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Trifolium dalmaticum | Balkan clover | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Trifolium dichotomum | branched Indian clover | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Trifolium dubium | lesser hop clover | Fabaceae | CT MA ME RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Trifolium echinatum | prickly clover | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Trifolium fragiferum | strawberry clover | Fabaceae | VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Trifolium glomeratum | clustered clover | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Trifolium hybridum | alsike clover | Fabaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Trifolium incarnatum | crimson clover | Fabaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Trifolium medium | zigzag clover | Fabaceae | MA ME VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Trifolium pratense | red clover | Fabaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Trifolium purpureum | purple clover | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Trifolium repens | white clover | Fabaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Trifolium resupinatum | Persian clover | Fabaceae | MA VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Trifolium striatum | knotted clover | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Trifolium subterraneum | burrowing clover | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Trifolium tomentosum | woolly clover | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Triglochin gaspensis | Gaspe Peninsula arrow-grass | Juncaginaceae | ME | Yes | Grass-like plants | All other grass-like plants | |
| Triglochin maritima | saltmarsh arrow-grass, seaside arrow-grass | Juncaginaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Triglochin palustre | marsh arrow-grass | Juncaginaceae | ME RI | Yes | Grass-like plants | All other grass-like plants | |
| Trigonella corniculata | cultivated fenugreek | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Trillium cernuum | nodding wakerobin, whip-poor-will flower | Melanthiaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Trillium erectum | red trillium, red wakerobin | Melanthiaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Trillium grandiflorum | white trillium, white wakerobin | Melanthiaceae | CT MA ME NH VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Trillium nivale | snow wakerobin | Melanthiaceae | CT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Trillium recurvatum | prairie wakerobin | Melanthiaceae | CT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Trillium undulatum | painted trillium, painted wakerobin | Melanthiaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Triodanis perfoliata | clasping-leaved Venus'-looking-glass | Campanulaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Triosteum angustifolium | lesser horse-gentian | Caprifoliaceae | CT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Triosteum aurantiacum | orange-fruited horse-gentian | Caprifoliaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Triosteum perfoliatum | perfoliate-leaved horse-gentian | Caprifoliaceae | CT MA RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Triphora trianthophora | three-birds orchid | Orchidaceae | CT MA ME NH VT | Yes | Orchids and related plants | Orchids | |
| Triplasis purpurea | purple sandgrass | Poaceae | CT MA ME NH RI | Yes | Grass-like plants | True grasses | |
| Tripleurospermum inodorum | corn scentless-chamomile | Asteraceae | CT MA ME NH | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Tripleurospermum maritimum | scentless-chamomile | Asteraceae | CT MA ME NH | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Tripsacum dactyloides | eastern gamagrass | Poaceae | CT MA RI | Yes | Grass-like plants | True grasses | |
| Triraphis mollis | purpleheads | Poaceae | MA | No | Grass-like plants | True grasses | |
| Trisetum flavescens | yellow false oat | Poaceae | MA VT | No | Grass-like plants | True grasses | |
| Trisetum spicatum | narrow false oat | Poaceae | MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Triticum aestivum | bread wheat | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Triticum turgidum | rivet wheat | Poaceae | CT | No | Grass-like plants | True grasses | |
| Trollius laxus | American globe-flower | Ranunculaceae | CT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Tropaeolum majus | garden-nasturtium | Tropaeolaceae | CT MA NH RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Tropidocarpum gracile | Dobie-pod | Brassicaceae | MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Tsuga canadensis | eastern hemlock | Pinaceae | CT MA ME NH RI VT | Yes | Woody Plants | Needle-leaved woody plants | |
| Tulipa gesneriana | Didier's tulip | Liliaceae | MA | No | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Tulipa sylvestris | wild tulip | Liliaceae | MA | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Turritis glabra | tower-mustard | Brassicaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Tussilago farfara | coltsfoot | Asteraceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Typha angustifolia | narrow-leaved cat-tail | Typhaceae | CT MA ME NH RI VT | No | Grass-like plants | All other grass-like plants | |
| Typha latifolia | broad-leaved cat-tail | Typhaceae | CT MA ME NH RI VT | Yes | Grass-like plants | All other grass-like plants | |
| Ulex europaeus | common gorse | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Ulmus americana | American elm | Ulmaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Ulmus glabra | Scotch elm | Ulmaceae | CT MA ME VT | No | Woody Plants | Broad-leaved woody plants | |
| Ulmus parvifolia | Chinese elm | Ulmaceae | MA | No | Woody Plants | Broad-leaved woody plants | |
| Ulmus procera | English elm | Ulmaceae | CT MA RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Ulmus pumila | Siberian elm | Ulmaceae | CT MA ME NH RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Ulmus rubra | slippery elm | Ulmaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Ulmus thomasii | rock elm | Ulmaceae | NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Urochloa texana | Texas liverseed grass | Poaceae | MA | Yes | Grass-like plants | True grasses | |
| Urtica dioica | stinging nettle | Urticaceae | CT MA ME NH RI VT | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Urtica urens | burning nettle | Urticaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Utricularia cornuta | horned bladderwort | Lentibulariaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Utricularia geminiscapa | mixed bladderwort | Lentibulariaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Utricularia gibba | creeping bladderwort | Lentibulariaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Utricularia inflata | swollen bladderwort | Lentibulariaceae | CT MA | Aquatic plants | Water plants with leaves and stems | ||
| Utricularia intermedia | flat-leaved bladderwort | Lentibulariaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants; Aquatic plants | Other herbaceous, flowering plants with alternate leaves; Water plants with leaves and stems | |
| Utricularia minor | lesser bladderwort | Lentibulariaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Utricularia purpurea | eastern purple bladderwort | Lentibulariaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Utricularia radiata | floating bladderwort | Lentibulariaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Utricularia resupinata | resupinate bladderwort | Lentibulariaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Utricularia striata | striped bladderwort | Lentibulariaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Utricularia subulata | slender bladderwort | Lentibulariaceae | MA RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Utricularia vulgaris | common bladderwort, greater bladderwort | Lentibulariaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Uvularia grandiflora | large-flowered bellwort | Colchicaceae | CT MA NH VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Uvularia perfoliata | perfoliate bellwort | Colchicaceae | CT MA NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Uvularia sessilifolia | sessile-leaved bellwort | Colchicaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Vaccaria hispanica | cowcockle | Caryophyllaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Vaccinium angustifolium | common lowbush blueberry | Ericaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Vaccinium boreale | northern blueberry | Ericaceae | ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Vaccinium caesariense | New Jersey highbush blueberry | Ericaceae | MA ME NH RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Vaccinium cespitosum | dwarf blueberry | Ericaceae | ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Vaccinium corymbosum | highbush blueberry | Ericaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Vaccinium fuscatum | black highbush blueberry | Ericaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Vaccinium macrocarpon | large cranberry | Ericaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Vaccinium myrtilloides | velvet-leaved blueberry | Ericaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Vaccinium oxycoccos | small cranberry | Ericaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Vaccinium pallidum | hillside blueberry | Ericaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Vaccinium stamineum | deerberry | Ericaceae | CT MA RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Vaccinium uliginosum | alpine blueberry | Ericaceae | ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Vaccinium vitis-idaea | mountain cranberry | Ericaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Vahlodea atropurpurea | arctic hair grass | Poaceae | ME NH | Yes | Grass-like plants | True grasses | |
| Valeriana officinalis | common valerian | Caprifoliaceae | CT MA ME NH VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Valeriana uliginosa | marsh valerian | Caprifoliaceae | ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Valerianella locusta | European corn-salad | Caprifoliaceae | CT ME | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Valerianella radiata | beaked corn-salad | Caprifoliaceae | CT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Valerianella umbilicata | navel corn-salad | Caprifoliaceae | CT MA | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Vallisneria americana | American eelgrass, tape-grass | Hydrocharitaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Ventenata dubia | North African grass | Poaceae | ME | No | Grass-like plants | True grasses | |
| Veratrum latifolium | slender bunch-flower | Melanthiaceae | CT | All other flowering non-woody plants; Orchids and related plants | Other herbaceous, flowering plants with opposite, whorled or no leaves; Irises, lilies, and other "monocots" | ||
| Veratrum viride | American false hellebore | Melanthiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants; Orchids and related plants | Other herbaceous, flowering plants with opposite, whorled or no leaves; Irises, lilies, and other "monocots" | |
| Verbascum blattaria | moth mullein | Scrophulariaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Verbascum densiflorum | dense-flowered mullein | Scrophulariaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Verbascum lychnitis | white mullein | Scrophulariaceae | CT MA NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Verbascum nigrum | black mullein | Scrophulariaceae | MA NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Verbascum phlomoides | orange mullein | Scrophulariaceae | CT MA ME RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Verbascum thapsus | common mullein | Scrophulariaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Verbena bonariensis | purple-topped vervain | Verbenaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Verbena bracteata | prostrate vervain | Verbenaceae | CT MA ME RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Verbena hastata | blue vervain | Verbenaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Verbena hispida | hairy mock-vervain | Verbenaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Verbena officinalis | European vervain | Verbenaceae | CT MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Verbena simplex | narrow-leaved vervain | Verbenaceae | CT MA VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Verbena stricta | hoary vervain | Verbenaceae | CT MA VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Verbena urticifolia | white vervain | Verbenaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Verbesina alternifolia | wingstem crownbeard | Asteraceae | CT MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Verbesina encelioides | golden crownbeard | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Vernonia fasciculata | prairie ironweed | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Vernonia glauca | broad-leaved ironweed | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Vernonia missurica | Missouri ironweed | Asteraceae | MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Vernonia noveboracensis | New York ironweed | Asteraceae | CT MA NH RI | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Veronica agrestis | green field speedwell | Plantaginaceae | CT MA ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Veronica americana | American speedwell | Plantaginaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Veronica anagallis-aquatica | blue water speedwell | Plantaginaceae | CT MA ME RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Veronica arvensis | corn speedwell | Plantaginaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Veronica austriaca | broad-leaved speedwell | Plantaginaceae | CT MA ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Veronica beccabunga | European speedwell | Plantaginaceae | CT MA ME | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Veronica catenata | water speedwell | Plantaginaceae | MA VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Veronica chamaedrys | germander speedwell | Plantaginaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Veronica filiformis | thread-stalked speedwell | Plantaginaceae | CT VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Veronica hederaefolia | ivy-leaved speedwell | Plantaginaceae | CT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Veronica longifolia | long-leaved speedwell | Plantaginaceae | CT MA ME NH RI VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Veronica officinalis | common speedwell | Plantaginaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Veronica peregrina | purslane speedwell | Plantaginaceae | CT MA ME NH RI VT | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Veronica persica | bird's-eye speedwell | Plantaginaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Veronica polita | gray field speedwell | Plantaginaceae | CT ME | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Veronica scutellata | narrow-leaved speedwell | Plantaginaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Veronica serpyllifolia | thyme-leaved speedwell | Plantaginaceae | CT MA ME NH RI VT | Yes and no (some introduced) | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Veronica spuria | bastard speedwell | Plantaginaceae | NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Veronicastrum virginicum | Culver's-root | Plantaginaceae | CT MA ME VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Veronica wormskjoldii | American alpine speedwell | Plantaginaceae | ME NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Viburnum acerifolium | maple-leaved viburnum | Adoxaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Viburnum dentatum | smooth arrowwood | Adoxaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Viburnum dilatatum | linden arrowwood | Adoxaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Viburnum edule | squashberry | Adoxaceae | ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Viburnum lantana | wayfaring tree | Adoxaceae | CT MA ME VT | No | Woody Plants | Broad-leaved woody plants | |
| Viburnum lantanoides | hobblebush | Adoxaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Viburnum lentago | nannyberry | Adoxaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Viburnum nudum | withe-rod | Adoxaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Viburnum opulus | highbush-cranberry | Adoxaceae | CT MA ME NH RI VT | Yes and no (some introduced) | Woody Plants | Broad-leaved woody plants | |
| Viburnum plicatum | Japanese snowball | Adoxaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Viburnum prunifolium | smooth blackhaw | Adoxaceae | CT | Yes | Woody Plants | Broad-leaved woody plants | |
| Viburnum rafinesquianum | downy arrowwood | Adoxaceae | CT MA NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Viburnum sieboldii | Siebold's arrowwood | Adoxaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Vicia cracca | bird vetch, cow vetch | Fabaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Vicia faba | broad vetch | Fabaceae | CT MA ME VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Vicia grandiflora | large yellow vetch | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Vicia hirsuta | tiny vetch | Fabaceae | CT MA ME NH RI | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Vicia lathyroides | spring vetch | Fabaceae | MA | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Vicia pannonica | Hungarian vetch | Fabaceae | CT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Vicia sativa | common vetch | Fabaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Vicia sepium | hedge vetch | Fabaceae | ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | ||
| Vicia tetrasperma | four-seeded vetch | Fabaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Vicia villosa | hairy vetch | Fabaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Vinca herbacea | herbaceous periwinkle | Apocynaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Vinca major | greater periwinkle | Apocynaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Vinca minor | lesser periwinkle | Apocynaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Viola adunca | hook-spurred violet | Violaceae | MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Viola affinis | Le Conte's violet | Violaceae | CT MA RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Viola arvensis | European field violet | Violaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Viola blanda | sweet white violet | Violaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Viola brittoniana | coast violet | Violaceae | CT MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Viola canadensis | Canada white violet | Violaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Viola cucullata | blue marsh violet | Violaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Viola hirsutula | southern woodland violet | Violaceae | CT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Viola japonica | Japanese violet | Violaceae | MA | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Viola labradorica | American dog violet, Labrador violet | Violaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Viola lanceolata | lance-leaved violet | Violaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Viola nephrophylla | northern bog violet | Violaceae | MA ME NH VT | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Viola novae-angliae | New England violet | Violaceae | ME | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Viola odorata | English violet | Violaceae | CT MA ME RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Viola pallens | smooth white violet | Violaceae | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | ||
| Viola palmata | wood violet | Violaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Viola palustris | northern marsh violet | Violaceae | ME NH | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Viola pectinata | pectinate-leaved violet | Violaceae | CT MA | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Viola pedata | bird-foot violet | Violaceae | CT MA NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Viola primulifolia | primrose-leaved violet | Violaceae | CT MA ME NH RI | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Viola pubescens | yellow forest violet | Violaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Viola renifolia | kidney-leaved violet | Violaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Viola rostrata | long-spurred violet | Violaceae | CT MA NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Viola rotundifolia | round-leaved violet | Violaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Viola sagittata | arrowhead violet | Violaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Viola selkirkii | great-spurred violet | Violaceae | CT MA ME NH VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Viola sororia | woolly blue violet | Violaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Viola striata | striped cream violet | Violaceae | CT MA NH RI | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Viola subsinuata | early blue violet | Violaceae | CT MA RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Viola tricolor | garden violet | Violaceae | CT MA ME NH RI VT | No | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Viscaria vulgaris | clammy-campion | Caryophyllaceae | CT MA ME NH | No | All other flowering non-woody plants | Other herbaceous, flowering plants with opposite, whorled or no leaves | |
| Vitis aestivalis | summer grape | Vitaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Vitis labrusca | fox grape | Vitaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Vitis palmata | catbird grape | Vitaceae | CT | Yes | Woody Plants | Broad-leaved woody plants | |
| Vitis riparia | river grape | Vitaceae | CT MA ME NH VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Vitis vinifera | European grape | Vitaceae | MA NH | No | Woody Plants | Broad-leaved woody plants | |
| Vitis vulpina | frost grape | Vitaceae | MA | Yes | Woody Plants | Broad-leaved woody plants | |
| Vulpia bromoides | brome six-weeks grass | Poaceae | MA | No | Grass-like plants | True grasses | |
| Vulpia myuros | rat-tail six-weeks grass | Poaceae | CT MA ME RI | No | Grass-like plants | True grasses | |
| Vulpia octoflora | eight-flowered six-weeks grass | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants | True grasses | |
| Weigela floribunda | crimson weigela | Caprifoliaceae | CT MA | No | Woody Plants | Broad-leaved woody plants | |
| Wisteria floribunda | Japanese wisteria | Fabaceae | MA ME NH | No | Woody Plants | Broad-leaved woody plants | |
| Wisteria frutescens | American wisteria | Fabaceae | CT MA RI | Yes | Woody Plants | Broad-leaved woody plants | |
| Wisteria sinensis | Chinese wisteria | Fabaceae | CT MA RI VT | No | Woody Plants | Broad-leaved woody plants | |
| Wolffia borealis | northern water-meal | Araceae | MA ME NH VT | Yes | Aquatic plants | Tiny water plants with no true stem | |
| Wolffia brasiliensis | Brazilian water-meal | Araceae | CT MA ME RI | Yes | Aquatic plants | Tiny water plants with no true stem | |
| Wolffia columbiana | Columbian water-meal | Araceae | CT MA ME NH RI VT | Yes | Aquatic plants | Tiny water plants with no true stem | |
| Wolffiella gladiata | sword-like bog-mat | Araceae | MA | Yes | Aquatic plants | Tiny water plants with no true stem | |
| Woodsia alpina | northern cliff fern | Woodsiaceae | ME VT | Yes | Ferns | True ferns and moonworts | |
| Woodsia glabella | smooth cliff fern | Woodsiaceae | MA ME NH VT | Yes | Ferns | True ferns and moonworts | |
| Woodsia ilvensis | rusty cliff fern | Woodsiaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Woodsia obtusa | blunt-lobed cliff fern | Woodsiaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Woodwardia areolata | netted chain fern | Blechnaceae | CT MA ME NH RI | Yes | Ferns | True ferns and moonworts | |
| Woodwardia virginica | Virginia chain fern | Blechnaceae | CT MA ME NH RI VT | Yes | Ferns | True ferns and moonworts | |
| Xanthium spinosum | spiny cocklebur | Asteraceae | CT MA ME NH RI | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Xanthium strumarium | rough cocklebur | Asteraceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | |
| Xanthorhiza simplicissima | shrub yellowroot | Ranunculaceae | CT MA ME | Yes | Woody Plants | Broad-leaved woody plants | |
| Xerochrysum bracteatum | bracted strawflower | Asteraceae | CT MA | All other flowering non-woody plants | Daisies, goldenrods, and other Aster family plants | ||
| Xyris difformis | bog yellow-eyed-grass | Xyridaceae | CT MA ME NH RI VT | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Xyris montana | northern yellow-eyed-grass | Xyridaceae | CT MA ME NH RI VT | Yes | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Xyris smalliana | Small's yellow-eyed-grass | Xyridaceae | CT MA ME RI | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Xyris torta | slender yellow-eyed-grass | Xyridaceae | CT MA NH RI | Orchids and related plants | Irises, lilies, and other "monocots" | ||
| Yucca filamentosa | Adam's-needle | Agavaceae | CT MA RI | No | Orchids and related plants | Irises, lilies, and other "monocots" | |
| Zannichellia palustris | horned-pondweed | Potamogetonaceae | CT MA ME NH RI VT | Yes | Aquatic plants | Water plants with leaves and stems | |
| Zanthoxylum americanum | common prickly-ash | Rutaceae | CT MA ME NH RI VT | Yes | Woody Plants | Broad-leaved woody plants | |
| Zea mays | corn | Poaceae | CT MA ME NH RI VT | No | Grass-like plants | True grasses | |
| Zizania aquatica | southern wild rice | Poaceae | CT MA ME NH RI VT | Yes | Aquatic plants; Grass-like plants | Water plants with leaves and stems; True grasses | |
| Zizania palustris | northern wild rice | Poaceae | CT MA ME NH RI VT | Yes | Grass-like plants; Aquatic plants | True grasses; Water plants with leaves and stems | |
| Zizia aptera | heart-leaved golden Alexanders | Apiaceae | CT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Zizia aurea | common golden Alexanders | Apiaceae | CT MA ME NH RI VT | Yes | All other flowering non-woody plants | Other herbaceous, flowering plants with alternate leaves | |
| Zostera marina | eel-grass, seawrack | Zosteraceae | CT MA ME NH RI | Yes | Aquatic plants | Water plants with leaves and stems |