Plants densely cespitose; rhizomes inconspicuous. Culms to 30 cm. Leaves: blades 1.5-3.5 mm wide. Inflorescences 1-12 cm, proximal internodes 5-50 mm; peduncles of proximal spikes to 5 cm; proximal bracts with blade 0-15(-40) mm, sheath cylindric, (3-)4-22 mm, mouth 0.5-1.2 mm wide. Spikes (2-)3-4(-5); lateral spikes pistillate, the proximal inclined or pendent, 6-21 × 3-6 mm; terminal spike gynecandrous, rarely staminate, pendent, 8-10 × 3.5-5 mm. Pistillate scales black or brown with pale, weak midvein and very narrowly scarious margins, ovate, 2.8-4.2 × 1.4-2.4 mm, apex obtuse to acuminate. Staminate scales brown to black with pale midvein and scarious margins, oblong-obovate to obovate, 3-5 × 1.4-1.8 mm. Anthers 1.2-2.7 mm. Perigynia ascending, pale brown proximally, black or dark brown distally, veins indistinct, lanceolate, 3.3-5.5 × 0.9-1.3(-1.4) mm, margins ciliate, glabrous; beak indistinct. Achenes obovoid, 1.5-2 × 0.9-1 mm.

Fruiting summer. Tundra, screes, sedge meadows; 50-2000 m; Greenland; Alta., B.C., Man., N.W.T., Que., Yukon; Alaska, Colo., Mont., Utah, Wyo.; Eurasia.

W. Dietrich (1967) recognized two subspecies in the alpine and artic regions of Europe, Carex fuligonosa subsp. fuliginosa, from the mountains of central Europe, with leaves about 1/2 as long as the fertile stems and spikes 15-20(-25) mm, and subsp. misandra (R. Brown) Nyman, from northern Europe, with leaves not more than 1/3 as long as the fertile stems and spikes 10-15 mm. The North American populations have traditionally been placed in subsp. misandra, but in North America many small plants with short spikes have culms scarcely exceeding the leaves; plants with long spikes have the leaves not more than 1/4 the length of the culms.