Distribution: Alaska south on both sides of the Cascades to California, east to Arizona and northeast United States.
Habitat: In rather shallow, standing water, often where brackish.
Flowers: May - August
Conservation Status: Not of concern
Aquatic, herbaceous perennials from slender rhizomes, the stems mostly unbranched, sub-terete, up to 2 mm. thick and 1.5 m. long.
Leaves alternate, the submersed leathery, sub-terete, narrowly linear, 10-20 cm. long and 1-2 mm. broad; floating leaves long-petioled, leathery, ovate-lanceolate to ovate-elliptic, rounded to nearly cordate at the base, 5-10 cm. long and 2.5-5 cm. broad, 19- to 35-nerved; stipules firm, fibrous, 4-10 cm. long.
: Flowers perfect, in densely-flowered spikes in 10-12 whorles, on stout 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 elliptic-obovoid, 3-5 mm. long, including the conical, stylar beak, rounded on the back.