Distribution: Alaska south on both sides of the Cascades to California, east through Canada to Newfoundland, south to New York and Indiana.
Habitat: In the Pacific Northwest, mostly in deep water of lakes.
Flowers: May - July
Conservation Status: Not of concern
Aquatic, herbaceous perennials from slender rhizomes, the stems up to 3 m. long, sparingly branched, slightly flattened, 2-3 mm. thick, whitish, the shorter internodes zigzag.
Leaves all submersed, the blades sessile, with a clasping base, oblong-lanceolate, 1-2.5 dm. long and 2-3 cm. broad, entire, the tip rounded and somewhat hooded; stipules free of the blade, 4-10 cm. long, whitish.
Flowers perfect, in dense spikes 2.5-5 cm. long; peduncles club-shaped, 1-3 dm. long; perianth of 4 clawed segments, each with an upturned, oval blade; stamens 4, fused with the claws; pistils 4, sessile.
Achenes obovoid, 4-5 mm. long, with a short beak and prominent dorsal keel.