Distribution: Alaska south along the coast west of the Cascades to Mendocino County, California.
Habitat: Marshes, ponds, ditches and rivers, often where submerged early in the season.
Flowers: July - September
Conservation Status: Not of concern
Perennial, often with floating leaves and stems, the stems tufted along slender rhizomes, 1-3 dm. tall, more or less decumbent and rooting at the nodes.
Leaves alternate, the blades semi-terete with prominent partitions, from firm and erect to filiform and lax; leaf bases sheathing, forming auricles 1-2 mm. long.
Heads 2-6 , 6-10 mm. broad, mostly 3- to 10-flowered, on loose peduncles, some of the flowers with short pedicles; perianth 3-4 mm. long, light to dark brown, the 6 segments subequal, narrowly lanceolate, pointed; stamens 3 or 6.
Capsule cylindric, narrowed to a short beak 1-1.5 mm. longer than the perianth.