Page authors: Don Knoke, David Giblin
Elodea canadensis
Canadian waterweed, common waterweed, Rocky Mountain waterweed

Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east across most of North America to the Atlantic Coast.

Habitat: Common in ponds, lakes, streams, rivers, and slow-moving waters.

Flowers: July-September

Origin: Native

Growth Duration: Perennial

Conservation Status: Not of concern

Pollination: Wind, water


Submerged, dioecious perennials, the stems sparingly branched dichotomously.


Leaves crowded, opposite below and in threes above, 6-15 mm. long and 1.5-2.5 mm. broad.


Staminate flowers solitary in fused bracts on long, slender, pedicle-like structures; sepals 3, greenish, 4 mm. long; petals 3, white, slightly longer than the sepals; stamens 9, the inner 3 on a short tube; pistillate flowers solitary in cylindric, fused bracts on slender, pedicle-like structures up to 15 cm. long; sepals 3, greenish, 2-2.5 mm. long; petals 3, white, equal to the sepals; staminodia 3, tooth-like, 0.5 mm. long; stigmas 3, 2-lobed.


Capsule about 6 mm. long.

Accepted Name:
Elodea canadensis Michx.
Publication: Flora Boreali-Americana. 1: 20. 1803.

Synonyms & Misapplications:
Elodea brandegeeae H. St. John
Elodea planchonii Casp. [Abrams]
Additional Resources:

PNW Herbaria: Specimen records of Elodea canadensis in the Consortium of Pacific Northwest Herbaria database

WA Flora Checklist: Elodea canadensis checklist entry

OregonFlora: Elodea canadensis information

E-Flora BC: Elodea canadensis atlas page

CalPhotos: Elodea canadensis photos

25 photographs:
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