Plants cespitose; rhizomes appearing elongate in old clumps. Culms uniformly slender, 40-80 cm; vegetative culms few, inconspicuous, usually fewer than 15 leaves, not strikingly 3-ranked. Leaves: sheaths adaxially conspicuously green-veined nearly to collar, narrow hyaline band or sharp Y-shaped region at collar, adaxially firm, summits U-shaped; distal ligules 1.6-3.3 mm; blades 2-5 per fertile culm, 12-18 cm × 1.5-2.5 mm. Inflorescences stiffly erect, dense to slightly open, brown, 1.5-3(-3.5) cm × 6-14 mm; proximal internode 2-12 mm; 2d internode 2-7 mm; proximal bracts scalelike, often with bristletips shorter than or equaling inflorescences. Spikes 2-5, distant, distinct, ovoid, 7-12 × 4-7 mm, base rounded or short-acute, apex acute. Pistillate scales reddish brown, 1-veined midstripe sometimes pale, broadly lanceolate, 2.7-3.6 mm, shorter and narrower than perigynia, apex firm, acute to acuminate. Perigynia 15-80 in larger spikes, appressed, usually golden brown, conspicuously 6-9-veined abaxially, inconspicuously veined adaxially, diamond shaped, flat except over achene, 4-5 × 2-2.8 mm, 0.4-0.5 mm thick, base subacute or acute, margin flat, including wing 0.6-0.9 mm wide, smooth; beak apprressed, golden brown at tip, flat, 0.7-1.6(-1.8) mm, 2/5+ length of body, ciliate-serrulate, abaxial suture with hyaline, golden brown margin, distance from beak tip to achene 2-3 mm. Achenes elliptic to ovate, 1.5-1.7 × 0.8-1.1 mm, 0.3-0.4 mm thick. 2n = 72. Fruiting early summer. Calcareous fens and seeps, shores, swales; 100-600 m; Ont.; Ark., Ill., Ind., Iowa, Mich., Minn., Mo., Ohio, Tex., Va., Wis., W.Va.
From Flora of Indiana (1940) by Charles C. Deam
Frequent to common, except in the southern counties, in open swamps, marshes, and moist ditches and on wet sandy borders of lakes. Not known from the unglaciated area.
Tufted, aphyllopodic, 3-7 dm; main lvs 2-3 mm wide, shorter or longer than the stem, their sheaths ventrally green-veined almost to the summit, with only a short hyaline area; spikes 2-5, gynaecandrous, ovoid, 7-12 mm, sessile, distinct but closely aggregated into an ovoid or short-oblong infl; pistillate scales shorter and narrower than the perigynia, yellowish-brown with pale midnerve and narrow hyaline margins, acute to cuspidate; perigynia numerous, appressed, prominently distended over the achene, 3.9-5.1 נ2.1-2.6 mm, 1.8-2.4 times as long as wide, broadest at a third to two-fifths their length, the broad body straight-tapered to the base, faintly nerved dorsally, nerveless or nearly so ventrally, abruptly contracted to the flat, serrulate beak; achene lenticular, 1.5 נ1 mm. Swamps and moist or wet meadows and shores, calciphile; s. Ont. to w. Va., s. Minn., and Mo.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.