Culms densely tufted, lateral, ascending or lax to decumbent, distinctly winged, 10-62 cm × 2-2.4 mm; basal sheath light brown to brown, the proximal frequently wine-red or purple, small, triangular. Leaves: sheaths 2-15 mm; blades ascending, midrib well developed, 2 lateral veins conspicuous, slightly more so than other veins, flat, thin, 10-35 cm × 10-38 mm, widest leaf 13-38(-62) mm wide, blades of overwintering leaves smooth. Inflorescences: peduncles of proximal spikes to 5.8 cm; of terminal spike absent. Bracts 1.4-2.6 cm × 3.9-2.2(-3.2) mm; bract blades of distal lateral spikes lanceolate or narrowly lanceolate, wider than spikes, concealing them, widest bract blade of distalmost lateral spike (2.9-)3.2-8.3 mm wide. Spikes 4(-5) per culm; lateral spikes 6-36 × 3-4.2 mm; terminal spike erect, linear, 4-18 × 1.2-1.6 mm, often hidden by distal 2 pistillate spikes and distal bract blade, frequently exceeded by distal 2 pistillate bracts. Pistillate scales oblong, 2.8-3.2 × 1.4-2 mm, apex obtuse or truncate, awnless (sometimes mucronate). Staminate scales oblong ovate, 2.8-3.2 × 1.4-2 mm, margins hyaline, apex obtuse. Anthers 2-2.2 mm. Perigynia 3-20 per spike, strongly to loosely overlapping, erect or ascending, obovate, 3-4.2 × 1.8-2.1 mm; beak abruptly bent, 0.3-0.6 mm. Achenes ovoid, 2.5-3.8 × 1.6-1.8 mm. 2n = 44. Fruiting spring. Moist deciduous or deciduous-evergreen forests, on steep slopes, or often, around limestone escarpments, washes, slides, or cave entrances; 100-1200 m; Ont., Que.; Ala., Ark., Conn., D.C., Ga., Ill., Ind., Iowa, Ky., Md., Mass., Mich., Minn., Mo., N.H., N.J., N.Y., N.C., Ohio, Okla., Pa., S.C., Tenn., Vt., Va., W.Va., Wis.
From Flora of Indiana (1940) by Charles C. Deam
Common on wooded slopes, chiefly in limestone areas; rare in low, moist or alluvial woods. Deam's collection of May 7, 1905, from Blackford County is exceptional in having the leaves semi-evergreen and rather rigid.
Tufted, 2-6 dm; fertile stems triangular and slightly winged, roughened on the angles; basal sheaths mostly brown, but the immediately suprabasal ones often purple; lvs of the sterile shoots 10-50 mm wide, of the fertile ones 4-16 mm; angles of the bract-sheaths minutely ciliate-serrulate; terminal spike staminate, 0.5-2 cm, sessile or nearly so, often hidden by the uppermost pistillate spike and its bract; pistillate spikes 3 or 4, 1-3 cm, the uppermost one or 2 near the staminate peduncle, the others remote, on short to elongate peduncles, none basal; pistillate scales broadly obtuse or subtruncate, only minutely apiculate; perigynia 3-20, ±overlapping, 3-4.2 mm, greenish-stramineous, finely many-nerved as well as 2-ribbed, obtusely trigonous, obovoid, with a short, abruptly bent beak; achene convexly trigonous; 2n=44. Rich woods, especially in calcareous regions; Vt. and s. Que. to Minn., s. to S.C. and Ark. (C. laxiflora var. latifolia)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.