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• Hydrocharitaceae
• Elodea
• Elodea nuttallii

Elodea nuttallii — free-flowered waterweed

Facts

Free-flowered waterweed is a native aquatic plant that is an invasive weed in Europe. It is named after Thomas Nuttall (1786-1859), a highly influential field botanist who collected widely across America, especially in the West.

Habitat

Lacustrine (in lakes or ponds), riverine (in rivers or streams)

Characteristics

• Clonal plantlets

  Turion length

  0 mm

• Flowers

  Anther color

  there is a noticeable pink, reddish or purplish tint to the anthers

  Anther length

  1–1.4 mm

  Carpels fused

  the carpels are fused to one another

  Flower lower lip length

  0 mm

  Flower number

  1

  Flower position

  • the flowers are above the surface of the water
  • the flowers are floating on the surface of the water

  Flower symmetry

  there are two or more ways to evenly divide the flower (the flower is radially symmetrical)

  Inflorescence type

  • the flowers grow out of the axil (point where a branch or leaf is attached to the main stem)
  • the inflorescence has only one flower on it

  Length of flower stalk

  Up to 90 mm

  Nectar spur

  the flower has no nectar spurs

  Ovary position

  • NA
  • the sepals and/or petals are attached above the ovary

  Palate on corolla

  no

  Petal and sepal arrangement

  the flower includes two cycles of petal- or sepal-like structures

  Petal color

  white

  Petal fringed edges

  the petals are not fringed

  Petal fusion

  the perianth parts are separate

  Petal length

  1–2.5 mm

  Petal number

  3

  Petal or sepal number

  there are three petals, sepals, or tepals in the flower

  Pistil number

  • 0
  • 1

  Sepal length

  Up to 2 mm

  Sepal number

  3

  Sepals fused only to sepals

  • the sepals are fused to each other (not other flower parts), at least near their bases
  • the sepals are separate from one another

  Spur length

  0 mm

  Stamen number

  9

  Stamen position relative to petals

  NA

  Stamens fused

  • the stamens are fused to one another at or near their bases
  • the stamens are not fused to one another

  Stamens fused to petals

  the stamens are not fused to the petals or tepals

  Style length

  1.2–2 mm

  Style number

  3

• Fruits or seeds

  Fruit length

  5–7 mm

  Fruit type (general)

  the fruit is fleshy

  Fruit type (specific)

  the fruit is a capsule (splits along two or more seams, apical teeth or pores when dry, to release two or more seeds)

  Fruit width

  1.5–2 mm

• Glands or sap

  Oil glands on nodes

  none of the nodes have oil glands

  Sap

  the sap is clear and watery

• Growth form

  Lifespan

  the plant lives more than two years

  Root septa

  the roots do not have transverse septa

  Roots floating in water

  there are no clusters of roots floating in the water

  Turions

  there are no turions on the plant

  Underground organs

  there are only slender roots on the plant

• Leaves

  Bract position (Sparganium)

  NA

  Bracts

  the flowers or their pedicels have bracts at their bases

  Floating leaf basal lobes

  NA

  Floating leaf blade width

  0 mm

  Floating leaf length

  0 mm

  Floating leaf shape

  NA

  Floating leaf tip

  NA

  Floral bract form

  the bracts are roughly as lobed as the foliage leaves

  Floral bract length

  2.2–15 mm

  Leaf arrangement

  whorled: there are three or more leaves per node along the stem

  Leaf blade length

  4–15.5 mm

  Leaf blade veins

  the lateral veins radiate from the base and continue to spread away from the centerline of the leaf, or branch off the central vein at intervals

  Leaf blade width

  0.9–2.4 mm

  Leaf position

  the leaves are all submerged underwater

  Leaf special features

  none of the mentioned special features are present

  Leaf-like branch segments

  0

  Leaf-like branch shape

  NA

  Specific leaf type

  the leaf is not divided, rather the blade is made up of one segment

  Staminate bract edge (Myriophyllum)

  NA

  Stipule appearance

  the stipules are delicate and translucent

  Stipules

  the plant has stipules

  Trap-bladder length

  0 mm

  Underwater leaf air passage number

  At least 1439

  Underwater leaf air passage relative width

  At least 4336

  Underwater leaf air passage row number

  0

  Underwater leaf blade edges

  the underwater leaf blade edges are toothed

  Underwater leaf blade shape

  • the underwater leaf blade is lanceolate (lance-shaped; widest below the middle and tapering at both ends)
  • the underwater leaf blade is linear (very narrow with more or less parallel sides)

  Underwater leaf blade veins

  1

  Underwater leaf blade width

  0.9–2.4 mm

  Underwater leaf length

  4–15.5 mm

  Underwater leaf stalk

  no

  Underwater leaf stalk length

  0 mm

  Underwater leaf tip shape

  the tip of the underwater leaf is acute (sharply pointed)

  Veins in floating leaf

  0

• Place

  Habitat

  aquatic

  New England state

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

  Specific habitat

  • in lakes or ponds
  • in rivers or streams

• Stem, shoot, branch

  Flowering stem growth form

  • the flowering stem is upright
  • the flowering stem trails along the substrate, or floats in the water

Wetland status

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

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae