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

Habitat: Ponds, lakes, and quiet streams.

Flowers: April-October

Origin: Introduced from Eurasia

Growth Duration: Perennial

Conservation Status: Not of concern

Pollination: Wind

Perennial, aquatic herbs, the stems simple or branched.

Leaves 1-3 cm. long, in whorls of 3-4, pinnately dissected into 13-23 filiform segments, abruptly reduced to the bract-like leaves of inflorescences.

Inflorescence emergent, simple; flowers single, subtended by bracts no longer than the fruit, the bracts serrulate to entire; sepals 4, attached to the top of the inferior ovary; petals 4, 2.5 mm. long, quickly deciduous; stamens 8 on the staminate flowers; stigmas short-hairy on the pistillate flowers.

Achene 2.5 mm. long, rounded.