Page authors: David Giblin, Don Knoke
Lemna trisulca
ivy duckweed, ivy-leaved duckweed, star duckweed

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

Habitat: Quiet streams and standing fresh water.

Flowers: July-September

Origin: Native

Growth Duration: Perennial

Conservation Status: Not of concern


Monoecious, fleshy, colonial perennials without stem or leaves, the plant a free-floating or submersed, oblong-elliptic to elliptic-lanceolate body 6-12 mm. long, with an equally-long, stalk-like base, the bodies tending to remain connected and forming large mats.




Plants rarely found in flower, reproducing vegetatively; flowers usually 3, 2 staminate and 1 pistillate, together in a marginal cleft of the body, the staminate a single stamen with a 2-celled anther, the pistillate a single carpel with a 1-celled ovary.


Fruit a utricle.

Accepted Name:
Lemna trisulca L.
Publication: Sp. Pl. 2: 970. 1753.

Synonyms & Misapplications:
(none provided)
Additional Resources:

PNW Herbaria: Specimen records of Lemna trisulca in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Lemna trisulca checklist entry.

E-Flora BC: Lemna trisulca atlas page.

CalPhotos: Lemna trisulca photos.

USDA Plants: Lemna trisulca information.

12 photographs:
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