Distribution: Occurring chiefly east of the Cascades crest along major rivers in Washington, however particularly common and rather invasives in lower Yakima River; British Columbia to California, widespread in eastern North America.
Habitat: River backwaters, slow-moving rivers, quiet streams, ponds and lakes.
Conservation Status: Not of concern
Submersed to partially floating perennial with freely-rooting, weak stems.
Leaves alternate, stipulate, linear, 7-15 cm. long and 2-5 mm. broad.
Flowers solitary, pale yellow, subtended by a bract, at the water surface; perianth tube very slender, 2-4 cm. long, the 6 lobes alike, linear, 5-mm. long; stamens 3; style 1, with 3 entire stigmas; ovary superior, 1-celled, with 3 parietal placentae.