Plants colonial from long-creeping rhizomes. Culms 20-60 cm × 0.5-0.8 mm, distally smooth. Leaves: blades trigonous-channeled in cross section, to 30 cm × 1-2 mm; distal leaf blade 1-4 cm × 1-1.5 mm, shorter than its 3.5-5.5 cm sheath. Inflorescences: blade-bearing involucral bracts solitary, similar to distal leaf, blade usually gray or black proximally, 0.6-2 cm. Spikelets (1-)2-5, in subumbels, narrowly ovoid, 7-10 mm in flower, 15-25 mm in fruit; peduncles 5-30 mm, scabrous; scales black or dark gray with black tip, broadly ovate, 3-4 mm, scarious, margins absent or to 0.1 mm wide, 5-9-ribbed, midrib prominent, usually dilated distally, reaching tip, apex obtuse-subacute. Flowers: perianth bristles 10 or more, white, 10-15 mm, smooth; anthers 1-2.5 mm. Achenes narrowly obovoid, 1.5-3 mm. Fruiting late spring-mid summer. Meadows, bogs, shores, usually peaty, acidic substrates; 0-4000 m; St. Pierre and Miquelon; Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Nunavut, Ont., P.E.I., Que., Sask.; Alaska, Calif., Colo., Conn., Del., Idaho, Ill., Ind., Maine, Mass., Mich., Minn., Mont., Nev., N.H., N.J., N.Y., Ohio, Oreg., Pa., R.I., Utah, Vt., Wash., Wis., Wyo.; Eurasia.