Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east to the Rocky Mountains, northern Great Plains, Great Lakes region, and eastern North America.

Habitat: Standing or running water.

Flowers: June-August

Origin: Native

Growth Duration: Perennial

Conservation Status: Not of concern

Pollination: Wind

Aquatic, herbaceous perennials from slender rhizomes, the slender stems freely branching, sub-terete, up to 2 m. long.

Leaves alternate, the submersed leaves sessile, linear to lanceolate or oblanceolate, 3-9 cm. long and 3-10 mm. broad, 3- to 7-nerved; floating leaves long-petiolate, elliptic to oblong-elliptic, 2-5 cm. long and 1-2 cm. broad, 13- to 19-nerved; stipules open, firm, up to 3 cm. long.

Flowers perfect, in 6-10 crowded whorls, in spikes 1.5-2.5 cm. long on peduncles 4-10 cm. long, stout, thickened upward; perianth of 4 clawed segments, each with an upturned, oval blade; stamens 4, fused with the claws; pistils 4, sessile.

Achenes obliquely obovoid, 2-2.8 mm. long including the short stylar beak, the dorsal keel well developed, the lateral ones obscure.