Culms erect or procumbent, to 20 cm. Leaves: blades 2-6 cm × 1-2.5 mm. Inflorescences: proximal bracts scalelike or leaflike, sheathless or with sheaths to 5 mm; lateral spikes with 5-25 perigynia, usually fastigiate, occasionally proximal distant, dense, 5-12 × 3.5-5.5 mm; middle internodes 0.2-0.4 mm; terminal spike gynecandrous, usually less than 1/3 of flowers staiminate, sessile, 6-11 mm, 1.1-1.8 mm wide in staminate portion. Pistillate scales ascending, ovate-circular, 1.9-2.5(-3) × 1.1-1.7 mm, apex obtuse, sometimes slightly mucronate. Staminate scales usually black or, rarely, dark brown with green midvein and hyaline margins, oblong-ovate, 2-3.5 mm, apex obtuse. Perigynia ascending, white, elliptic-ovate, 1.8-3 × 1-1.8 mm, densely papillose. Achenes obovate, 1.4-2 × 1-1.6 mm. 2n = ca. 52.

Fruiting summer. Moist tundra, usually calcareous, rocks and soils; 0-500 m; Greenland; B.C., Man., Nfld. and Labr. (Nfld.), N.W.T., Nunavut, Ont., Que., Sask.; Alaska; Europe; Asia.