Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east to the Rocky Mountains; also in northeastern North America; Europe.

Habitat: Shallow to deep water.

Flowers: June-August

Origin: Native

Growth Duration: Perennial

Conservation Status: Not of concern

Pollination: Wind, self-pollination

Aquatic, perennial herbs from slender rhizomes, the stems somewht flattened, simple or sparingly branched, 5-15 dm. long.

Submersed leaves linear, sessile, 10-20 cm. long and 3-10 mm. broad, the mid-vein bordered by rows of air chambers; floating leaves with flattened petioles shorter than the blade, the blades firm, elliptic to oblong-elliptic, 4-8 cm. long and 10-20 mm. broad, 15- to 25-nerved; stipules free, 1-3 cm. long, blunt.

Flowers in dense spikes 2-4 cm. long, on peduncles 3-8 cm. long; perianth of 4 clawed segments, each with an upturned, oval blade; stamens 4, fused with the claws; pistils 4, sessile.

Achenes obliquely and broadly obovate, 3-4 mm. long, sharply keeled on the back.