Herbs, perennial, loosely cespitose, 0.25--1.6 dm. Culms nearly terete. Cataphylls 2--4. Leaves basal, 1--4; sheaths loose; auricles absent or rounded, 0.5 mm; blade imperfectly septate, ascending, nearly terete, 2--7 cm x 0.5--1.5 mm. Inflorescences heads, 1--2(--4)-flowered; primary bracts much longer than inflorescence. Flowers: tepals brown to blackish, oblong, 2.5--4 mm, apex obtuse; outer and inner series nearly equal; stamens 6, filaments 1--1.5 mm, anthers 0.5--0.7 mm; style deciduous, 0.3--0.4 mm. Capsules pale with dark purplish valve margins, pseudo-3-locular, oblate to narrowly ovoid, 4--5.5 x 1.7--2.3 mm, exceeding perianth, apex retuse. Seeds yellowish tan, fusiform-ovoid, 0.7--0.9 mm, short tailed. 2n = 120.

Flowering and fruiting summer. Wet tundra and mossy margins of ponds and streams, wet gravel and open, rocky slopes in alpine zones; 10--3400 m; Greenland; Alta., B.C., Man., Nfld. and Labr. (Labr.), N.W.T., Nunavut, Ont., Que., Yukon; Alaska, Colo., Mont., Wyo.; n Europe; Asia..