Distribution: East of the Cascades in Washington; British Columbia south to California, east to New York.
Habitat: Ponds, lake shores and ditches.
Conservation Status: Not of concern
Aquatic, scapose, tuber-bearing perennial from strong rhizomes, the scapes up to 5 dm. long.
Leaves mostly emersed or the blades floating, but sometimes submerged; emersed leaves with sagittate blades 1-12 cm. long and up to 6 cm. broad; floating leaves linear or ovate; submerged leaves linear, up to 4 dm. long and 2-10 mm. broad.
Flowers in whorles of 3 in bracteate racemes, the bracts lanceolate, 5-30 mm. long; lower whorles pistillate, the pedicles 5-20 mm. long, ascending, longer in the staminate flowers in the upper whorles; sepals 3, 5-8 mm. long, persistent; petals 3, white, longer than the sepals; stamens 15-25; pistils many on a globose receptacle.
Achenes 2-2.5 mm. long, winged, the stylar beak straight, 0.2-0.4 mm. long.