Distribution: Occurring on both sides of the Cascades crest in Washington; Northwest Territories south to California, east across North America in scattered locations to the Atlantic Coast.
Habitat: Ponds and lakes, usually in rather deep, quiet water.
Conservation Status: Not of concern
Aquatic, herbaceous perennials from slender rhizomes, the stems simple to freely branched, terete, up to 2 m. long.
Leaves alternate, the submersed leaves thin, lanceolate to elliptic or oblanceolate, 10-20 cm. long and 2-4 cm. broad, sub-sessile or tapered to a short petiole, prominently 9- to 19-nerved; floating leaves, if any, rather firm, transitional to the submersed leaves; stipules 3-7 cm. long.
Flowers perfect, in compactly-flowered spikes 3-6 cm. long, on peduncles 4-12 cm. long, thicker than the stem; perianth of 4 clawed segments, each with an upturned, oval blade; stamens 4, fused with the claws; pistils 4, sessile.
Achenes broadly obliquely obovoid, 4 mm. long including the short beak, the dorsal keel prominent and sharp, the lateral keels also prominent.