Culms 5-35 cm. Leaves: basal sheaths dull, base of blade usually persistent; blades ± channeled, 2-20 cm × 0.2-1.5(-2) mm. Inflorescences usually compound, (8-) 10-35 × (2-)3-8 mm; bracts brown, margins hyaline, ovate to oblong-ovate; proximal spikelets 1-flowered and pistillate or 2-flowered and androgynous; terminal and distal spikelets 1-flowered, staminate. Scales brown, ovate, 2-3 mm, margins hyaline, midvein distinct almost to tip, apex obtuse to subacute. Anthers 1-2 mm. Perigynia brown, 2.5-3.2 mm, margins free to base, smooth. Achenes 2-3 mm. 2n = 70-75.

Fruiting summer. Fens, marshes, mesic to wet tundra, gravels, rocky slopes, usually on calcareous substrates; 0-3500 m; Greenland; Alta., B.C., Man., Nfld. and Labr., N.W.T., Nunavut, Ont., Que., Yukon; Alaska, Colo., Idaho, Oreg., Utah, Wyo.; Eurasia.