Plants loosely cespitose; rhizomes long, slender. Culms grooved, terete, 5-14 cm, smooth. Leaves: basal sheaths brown; distal leaf sheaths truncate to concave at mouth; blades 2-8.4 × 0.4-0.5 mm, much shorter than culms at flowering and fruiting. Inflorescences: spikelets 3-6-flowered, 3-4.6 × 1.7-2.8 mm; bracts shorter than spikelets, 1.6-2.5 mm, apex mucronate. Spikelets: scales brown, apex obtuse. Flowers: perianth bristles absent; anthers 0.8-1.5 mm. Achenes compressed trigonous to plano-convex, (1.2-)1.4-1.9 × 0.8-1.2 mm. Fruiting summer (Jul-Aug). Moist to wet coniferous swamps, bogs, riverbanks; calciphile; 20-1500 m [3500 m, Nepal]; Alta., B.C., N.W.T., Que., Sask., Yukon; Alaska, Calif., Mont.; Europe; c Asia. North American plants have been distinguished as Trichophorum pumilum var. rollandii (Fernald) Beetle; differences from the Eurasian plants are elusive. The chromosome number in Europe is 2n = 78.