Elodea canadensis Michx.

common waterweed

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New England Distribution

Adapted from BONAP data

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North America Distribution

Adapted from BONAP data

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Facts About

Common water-weed can grow completely submersed in deep water or partially emersed in shallower water. It rarely produces seeds, the principal means of reproduction being stem fragments that grow into a new plant.

Habitat

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

Characteristics

Habitat
aquatic
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Leaf position
the leaves are all submerged underwater
Leaf arrangement
  • opposite: there are two leaves per node along the stem
  • whorled: there are three or more leaves per node along the stem
Leaf blade length
5–13 mm
Petal or sepal number
there are three petals, sepals, or tepals in the flower
Petal color
white
Specific leaf type
the leaf is not divided, rather the blade is made up of one segment
Floating leaf shape
NA
Underwater leaf blade width
1.1–5 mm
Fruit type (general)
the fruit is dry and splits open when ripe
Underwater leaf length
5–13 mm
Show All Characteristics
  • Clonal plantlets
    Turion length
    0 mm
  • Flowers
    Anther length
    1.7–3 mm
    Carpels fused
    the carpels are fused to one another
    Flower lower lip length
    0 mm
    Flower number
    1
    Flower position
    • the flowers are below 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 length
    2–4 mm
    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
    20–300 mm
    Length of peduncle
    20–300 mm
    Nectar spur
    the flower has no nectar spurs
    Number of carpels
    0–6
    Ovary position
    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 appearance
    the petals are thin and delicate, and pigmented (colored other than green or brown)
    Petal color
    white
    Petal fringed edges
    the petals are not fringed
    Petal fusion
    the perianth parts are separate
    Petal hairs on inner/upper surface
    there are no hairs on the inner/upper petal surface
    Petal length
    2–4.5 mm
    Petal number
    3
    Petal or sepal number
    there are three petals, sepals, or tepals in the flower
    Pistil number
    • 0
    • 1
    Sepal appearance
    the sepals resemble leaves in color and texture
    Sepal length
    2–4 mm
    Sepal number
    3
    Sepals fused only to sepals
    the sepals are separate from one another
    Spur length
    0 mm
    Stamen number
    • 3
    • 7
    • 8
    • 9
    Stamen position relative to petals
    NA
    Stamens fused
    the stamens are fused to one another at or near their bases
    Stamens fused to petals
    the stamens are not fused to the petals or tepals
    Style length
    2.6–4 mm
    Style number
    0–3
  • Fruits or seeds
    Fruit beak length
    5–6 mm
    Fruit length
    5–6.5 mm
    Fruit type (general)
    the fruit is dry and splits open when ripe
    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
    3 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
    Bract relative length
    At least 3854 mm
    Bracts
    neither the flowers nor their pedicels have bracts
    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
    NA
    Floral bract length
    0 mm
    Leaf arrangement
    • opposite: there are two leaves per node along the stem
    • whorled: there are three or more leaves per node along the stem
    Leaf blade length
    5–13 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
    1.1–5 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
    Stipules fused around stem
    the stipules form a completely closed tube around the stem
    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 elliptic (widest near the middle and tapering at both ends)
    • 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)
    • the underwater leaf blade is oblong (rectangular but with rounded ends)
    • the underwater leaf blade is ovate (widest below the middle and broadly tapering at both ends)
    • the underwater leaf blade is subulate (awl-shaped; narrowly tapering from the base to the tip)
    Underwater leaf blade veins
    1
    Underwater leaf blade width
    1.1–5 mm
    Underwater leaf length
    5–13 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)
    • the tip of the underwater leaf is obtuse (bluntly 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 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

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.

Massachusetts
unranked (S-rank: SNR)

Native to North America?

Yes

Sometimes Confused With

Elodea nuttallii:
leaves 0.9-1.7 mm wide, flaccid, pointed at the apex (vs. E. canadensis, with leaves 1.1-5 mm wide, firm, blunt at the apex).

Synonyms

  • Anacharis canadensis (Michx.) Planch.

Genus

Elodea

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Information from Dichotomous Key of Flora Novae Angliae

1.  Elodea canadensis Michx. N

common waterweed. Anacharis canadensis (Michx.) Planch. • CT, MA, ME, NH, RI, VT. Shallow, 
still or slow-moving, circumneutral to basic waters of lakes and rivers.