Plants densely cespitose. Culms 20-104 cm. Leaves: sheath white-hyaline, summits usually U-shaped, sometimes rounded and prolonged to 3 mm beyond collar; distal ligules 1-3(-6) mm; blades 3-5(-8) per fertile culm, 6-45 cm × 1.2-3(-3.7) mm. Inflorescences open or dense, green to brown, 1.1-3 cm × 5.4-16.3 mm, appearing fine-textured; proximal internode (1.5-)2.5-9.5 mm; 2d internode 1-3(-6) mm; proximal bracts scalelike or bristlelike shorter than inflorescences. Spikes 4-11(-14), densely or loosely aggregated, broadly ovoid to ovoid, 5-11 × 2.7-7.1 mm, base rounded or acute, apex usually rounded. Pistillate scales usually white-hyaline or hyaline gold, occasionally chestnut to dark brown, with pale to green midstripe, ovate to broad-ovate, 2.1-3.5(-3.9) mm, shorter than or ± covering perigynia, margin white, 0-0.2 mm wide, apex obtuse to acuminate. Perigynia ascending to spreading, green, straw colored to light brown, or whitish, conspicuously (0-)2-8(-11)-veined abaxially, conspicuously 0-6-veined adaxially, veins thick, reaching, not extending beyong top of achene, lance-ovate to ovate, plano-convex, 2.4-4(-4.3) × 0.9-1.9 mm, 0.4-0.5(-0.6) mm thick, 2.1-2.7 times as long as wide, margin flat, including wing 0.15-0.3(-0.45) mm wide, ciliate-serrulate at least on distal body; beak green, gold, brown or white-hyaline at tip, flat, ± ciliate-serrulate or cylindric, unwinged, ± entire for 0.4-0.7 mm, abaxial suture usually inconspicuous, distance from beak tip to achene 1.2-2 mm. Achenes elliptic to quadrate, 1-1.6 × 0.7-1.25 mm, (0.3-)0.4-0.5(-0.6) mm thick. 2n = 84. Fruiting summer. Seasonally moist mountain meadows, along watercourses; 100-3500 m; Ariz., Calif., Idaho, Nev., N.Mex., Oreg., Utah, Wash.; Mexico (Baja California); Pacific Islands (Hawaii).