Plants densely cespitose; rhizomes short. Culms erect, slender, 15-80 cm, very rough distally. Leaves: sheaths pale to gray-brown abaxially, inner band thin, hyaline, conspicuously purplish dotted, concave at summit; ligules acute, longer than wide; blades pale to gray-green, flat, 15-50 cm × 2-4 mm, shorter than to exceeding culms. Inflorescences erect, ovoid-oblong, 1.5-4 cm × 7-12 mm; proximal bracts (sometimes also 2d) bristlelike-prolonged, from short to clearly exceeding spikes, distal bracts usually scalelike. Spikes 5-15, gynecandrous, proximal often slightly separate, distal closely approximate (sometimes hardly recognizable), containing 10-20 perigynia, sessile, oblong, 5-10 × 4-6 mm. Pistillate scales hyaline with green center, often brown tinged, ovate, shorter than perigynia, apex obtuse to short-cuspidate. Perigynia spreading-ascending, greenish, often brown in age, several-veined, ovate, widest near base, 2-3(-3.5) × 1.25-1.5 mm, minutely papillose (membranous); beak abaxial suture conspicuous, 0.75-1.25 mm, margin serrulate. Achenes pale brown, ovate, 1.25-1.5 1 mm, dull to slightly glossy. 2n = 60. Fruiting Jun-Sep. Swampy (coniferous) woods and thickets, wet meadows; 0-2000 m; Alta., B.C., Man., N.B., Ont., Que., Yukon; Calif., Idaho, Maine, Mass., Mich., Minn., Mont., N.H., N.Y., Oreg., Vt., Wash., Wis.
Stems densely tufted, (1-)3-6 dm, sharply triangular, scabrous on the angles above; lvs all on the lower part of the stem but not closely tufted, ±flat, 1.5-4 mm wide, elongate, often surpassing the stems; spikes 7-15, gynaecandrous, sessile, 5-10 mm, all ±closely aggregated into a pale greenish to brownish-green, narrowly ovoid to cylindric head 1.5-4 cm; bracts short and inconspicuous, or the lowest ones setaceous and to 5 cm; perigynia (20-)25-40, ±strongly spreading, planoconvex, somewhat spongy at base, ovate or lance-ovate, 2.2-3.4 mm, several-nerved dorsally, few-nerved or nerveless ventrally, with a prominent, serrulate-margined beak 0.6-1.2 mm; achene lenticular; 2n=60. Streambanks, meadows, and other wet places; Que. to s. Yukon, s. to N.Y., Mich., Minn., and Calif.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.