Distribution: Widely distributed on both sides of the Cascades crest in Washington; Alaska to California, east to the Rocky Mountain, northern Great Plains, Great Lakes region, and northeastern North America.

Habitat: Streams, ponds and shallow lakes, generally at least partially emerged.

Flowers: June-August

Origin: Native

Growth Duration: Perennial

Conservation Status: Not of concern

Pollination: Wind

Glabrous, aquatic perennials with creeping rhizomes, the erect branches partly emersed, 1.5-2.5 mm. thick and 5-30 cm. long, usually simple, but frequently with short branches from the lower nodes.

Leaves linear, entire, 6-12 per whorl, 1-2 mm. broad and 10-35 mm. long.

Flowers mostly perfect, sessile and solitary in the leaf axils; perianth none; stamen 1; pistil 1-celled; style slender, stigmatic the entire length, lying in the groove between the lobes of the large anther.

Fruit nut-like, 1-seeded.