Herbs, perennial, not cespitose, rhizomatous, 2.5--8.5 dm. Rhizomes 2--3 mm, tuberous. Culms erect, terete, 1--3 mm diam., smooth. Cataphylls 1--2, straw-colored, apex acute. Leaves: basal 0--1, cauline 2--3, auricles 2--3 mm, apex acute, membranaceous; blade green to straw-colored, terete, 7--28 cm x 1--2 mm. Inflorescences terminal racemes of 1--8 heads or single head, 1--13 cm, branches ascending to spreading; primary bract erect; heads 40--70-flowered, spheric, 7--11 mm diam. Flowers: tepals dark reddish brown to light brown, lance-subulate, (2.6--)3--3.5(--4) mm, apex acuminate; stamens 3, anthers 1/4 filament length. Capsules equaling perianth or slightly included, chestnut brown, 1-locular, ellipsoid to oblong, 3--3.5 mm, apex acuminate, valves separating at dehiscence, fertile throughout or only proximal to middle. Seeds oblong, 0.4--0.5 mm, not tailed; body clear yellow-brown.

Fruiting late spring--summer. Swamps, marshes, stream banks, beaches, roadside meadows, and other moist or wet areas; 0--1000 m.; B.C.; Calif., Idaho, Oreg., Wash.; nw Mexico.