Distribution: Widespread in North America; British Columbia south the California, east to the Atlantic Coast.
Habitat: Ponds and quiet streams, often in brackish water.
Flowers: June - August
Conservation Status: Not of concern
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.