Plants loosely to densely cespitose. Culms 21-67 cm × 0.7-1.4 mm, smooth or papillose. Leaves: ligule of distal leaf (2.5-)3.4-6.8(-7.4) mm, 1.5-3 times as long as wide; blades 2.4-5.9 mm wide, widest blade 2.8-5.9 mm wide. Inflorescences (17-)34-43(-68) mm; proximal internode 4.1-16(-40) mm; proximal bract (11-)16-26(-61) mm, awn (9-)13-23(-59) mm; spikes 5-7, usually gynecandrous; proximal spikes with 2 staminate and 11-23 pistillate flowers, 8-15 × 3.3-5.8 mm; terminal spikes usually with 2-4 staminate and 16-20 pistillate flowers, 9-12.7 × 4.2-5.7 mm. Pistillate scales with whitish to stramineous margins, 2.6-3.3 × 1.2-1.8 mm, body (2.3-)2.7-3.8, apex acuminate to short-awned, awn to 0.7 mm. Staminate scales with whitish to stramineous margins, 1.9-2.8 × 1-1.3 mm. Anthers 1.8-1.9 mm. Perigynia ascending to erect, green to pale brown, 0-3-veined abaxially, prominently to weakly 0-2-veined adaxially, ovate to narrowly ovate, 3.3-3.9(-4.4) × 1.1-1.5 mm, 2.3-3 times as long as wide, apex abruptly contracted to gradually tapering; beak 0.9-1.5(-1.7) mm, (0.28-)0.3-0.38 times as long as perigynia, margins serrulate, apex entire or bidentulate, teeth to 0.3 mm, 0-0.08 times as long as perigynia. Stigmas 1.3-1.8 mm. Achenes 1.5-1.8(-1.9) × 0.9-1.4 mm, 1.2-1.5(-1.7) times as long as wide. 2n = 54.

Fruiting spring-summer. Mesic to wet forests, forest edges, especially near streams; 0-2500 m; B.C.; Calif., Idaho, Mont., Oreg., Wash.