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Triglochin maritima — saltmarsh arrow-grass, seaside arrow-grass

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Facts

Saltmarsh arrow-grass is native to North America, South America, Europe and parts of Asia. It is found in salt and brackish marshes and fens in all New England states. It is toxic to livestock due to production of cyanide in the leaves. Experiments in salt marshes in New England indicate that arrow-grass is an ecosystem engineer, enhancing plant diversity. Its dense root mat creates a ring of elevated soil, free from water-logging, that other plant species can colonize.

Habitat

Brackish or salt marshes and flats, fens (calcium-rich wetlands), fresh tidal marshes or flats, marshes, intertidal, subtidal or open ocean, wetland margins (edges of wetlands)

New England distribution

Adapted from BONAP data

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North America distribution

Adapted from BONAP data

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Characteristics

Habitat
  • aquatic
  • wetlands
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Stem shape in cross-section
the stem is round or oval in cross-section
Leaf blade width
0.9–1.4 mm
Leaf blade cross-section
the leaf blade is elliptic or circular in cross-section
Inflorescence position
the inflorescence is at the tip of the plant
Inflorescence branching
the inflorescence is on one or more stems with no branches
Fruit type (general)
the fruit is a capsule, with at least three seeds in it
Fruit length
2–4.5 mm
Leaf position on plant
the attachment points of all the leaves are at or near the base of the plant
Perianth composition
the perianth is green or brown, with six sepal-like parts, and a leafy texture
Fruit cross-section
the fruit is triangular to terete (circular) in cross-section
Show all characteristics

  • Flowers

    Floral bristle color
    NA
    Floral bristle number
    NA
    Floral bristle relative length
    NA
    Floral bristles
    NA
    Floral scale hairs
    NA
    Floral scale length
    0 mm
    Floral scale nerves
    NA
    Inflorescence bract angle
    NA
    Inflorescence bract number
    NA
    Inflorescence bract position (Sparganium)
    NA
    Inflorescence bracts
    NA
    Inflorescence branching
    the inflorescence is on one or more stems with no branches
    Inflorescence crowding
    the inflorescence is at least somewhat spread out, with at least one branch coming from the main stem
    Inflorescence position
    the inflorescence is at the tip of the plant
    Inflorescence shape
    the aggregations within the inflorescence are roughly circular (not flattened) in cross-section
    Inflorescence type
    there is one spike or raceme at the tip of the stem
    Perianth composition
    the perianth is green or brown, with six sepal-like parts, and a leafy texture
    Stamen number
    4-6
    Stigma number
    • 3
    • more than 3
    Style division
    NA
    floral bristle barbs
    NA

  • Fruits or seeds

    Achene beak length
    0 mm
    Achene surface texture
    NA
    Achene tubercle relative width
    NA
    Achene tubercle width
    0 mm
    Capsule relative length
    NA
    Fruit cross-section
    the fruit is triangular to terete (circular) in cross-section
    Fruit length
    2–4.5 mm
    Fruit type (general)
    the fruit is a capsule, with at least three seeds in it
    Fruit type (specific)
    • the fruit is a non-wind-dispersed follicle (has one ovary that splits along one side to release the seeds)
    • the fruit is a schizocarp (when dry it splits into sections, each holding one or more seeds)
    Locules in capsule
    NA
    Seed length
    0 mm
    Seed tail relative length
    0 mm
    Seed tails
    NA
    Tubercle height
    0 mm

  • Growth form

    Lifespan
    the plant lives more than two years
    Underground organs
    the plant has a rhizome (a horizontal underground stem with roots growing from it)

  • Leaves

    Auricle texture
    the auricles are weak, papery and translucent
    Auricles
    the leaf sheath has auricles on it
    Leaf blade cross-section
    the leaf blade is elliptic or circular in cross-section
    Leaf blade length
    22–115 mm
    Leaf blade width
    0.9–1.4 mm
    Leaf form
    all the leaves hold their form out of water
    Leaf position on plant
    the attachment points of all the leaves are at or near the base of the plant
    Leaf septa
    the leaf blades do not have transverse septa
    Leaf sheath hairs
    the leaf sheathes are without hairs
    Pedicel length (Typha)
    0 mm
    Stem leaf blade ligules
    the plant has ligules at the leaf blade bases
    Stem leaf blades
    there are fully-developed leaves with leaf blades on the main stem
    Width of seed-producing inflorescence
    1.5–7 mm

  • Place

    Habitat
    • aquatic
    • wetlands
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • brackish or salt marshes and flats
    • edges of wetlands
    • fens (calcium-rich wetlands)
    • fresh tidal marshes or flats
    • intertidal, subtidal or open ocean
    • marshes

  • Stem, shoot, branch

    Plant height
    3.5–61.5 cm
    Stem shape in cross-section
    the stem is round or oval in cross-section
    Stem texture near tip
    the stem feels smooth near the tip

Wetland status

Occurs only in wetlands. (Wetland indicator code: OBL)

In New England

Distribution

Connecticut
present
Maine
present
Massachusetts
present
New Hampshire
present
Rhode Island
present
Vermont
present

Conservation status

Exact status definitions can vary from state to state. For details, please check with your state.

Vermont
extremely rare (S-rank: S1), endangered (code: E)

From Flora Novae Angliae dichotomous key

2.  Triglochin maritima L. N

saltmarsh arrow-grass. Triglochin debilis (M.E. Jones) A. & D. Löve; T. maritima L. var. elata (Nutt.) Gray • CT, MA, ME, NH, RI, VT. Saline and brackish marshes, fens.

Native to North America?

Yes

Sometimes confused with

Trigolochin palustre:
mature fruits mostly 5-7 times as long as wide, with 3 stigmas (vs. T. maritima, with mature fruits mostly 2 times as long as wide, with 6 stigmas).

Synonyms

  • Triglochin debilis (M.E. Jones) A. & D. Löve
  • Triglochin maritima var. elata (Nutt.) Gray

Family

Juncaginaceae

Genus

Triglochin