Plants densely to loosely cespitose. Culms 31-115 cm × 0.9-2 mm, smooth, serrulate, or scabriduous at mid height. Leaves: ligule of distal leaf (2-)3.5-7.1 mm, 2-3.9 times as long as wide; blades 1.8-5.9 mm wide, widest blade 2.3-5.9 mm wide. Inflorescences (33-)40-89(-103) mm; proximal internode 6-32 mm; proximal bracts 14-43 mm, awn 10-39 mm; spikes 5-9, usually gynecandrous; proximal spikes usually with 1-4 staminate and (14-)18-31(-40) pistillate flowers, 12-22(-25) × 3.9-6.5 mm; terminal spikes usually with 1-5 staminate and 14-28 pistillate flowers, 9.6-16 × 3.4-6.2 mm. Pistillate scales with whitish to castaneous margins, (2.2-)2.5-4.1 × 1.4-2 mm, body 2.2-2.9(-3.1) mm, apex acuminate to short-awned to 1.5 mm. Staminate scales with whitish to castaneous margins, 3.1-4.3 × 1-1.5 mm, apex acute to short-awned. Anthers 1.3-1.8 mm. Perigynia erect to appressed-erect, green to brown, prominently to weakly 3-7-veined abaxially, prominently to weakly 0-3(-6)-veined adaxially, narrowly lanceolate, 3.4-5.2 × 1.1-1.4 mm, 2.9-4 times as long as wide, apex abruptly contracted to gradually tapering; beak 1.5-2.5 mm, 0.4-0.53 times as long as perigynia, margins serrulate, apex bidentulate, teeth (0.2-)0.3-1 mm, (0.06-)0.09-0.2 times as long as perigynia. Stigmas 1.8-2.5 mm. Achenes 1.5-2.1 × 0.9-1.3 mm, 1.3-1.8 times as long as wide.

Fruiting spring-summer. Mesic to wet forests, forest edges, especially near streams; 30-2500 m; B.C.; Ariz., Calif., Idaho, Mont., Nev., N.Mex., Oreg., Utah, Wash.; Mexico (Chihuahua, Durango).