Culms 10-110 cm. Leaves 3-5 per culm; sheaths tight, inner band hyaline, 3.5-24 cm, apex concave, glabrous; ligules rounded to obtuse, 0.5-3.7 mm; blades plicate, 8-60 cm × 0.4-4(-4.5) mm, widest leaf 0.8-4(-4.5) mm wide. Inflorescences 0.8-5.5 cm; spikes 2-8; lateral spikes pistillate often with a few staminate flowers proximally, 3.1-13.1 mm, sessile, staminate portion 10-flowered, to 6.5 mm, pistillate portion 3-40-flowered, 2.5-12 mm; basal 2 spikes 1.5-18 mm apart; terminal spike gynecandrous, 4.8-23.7 mm, staminate portion 2-21-flowered, 1.8-13.5 × 0.8-1.3 mm, pistillate portion 4-38-flowered, 3-11 × 4.4-7.5 mm. Pistillate scales ovate to ± suborbicular, 1.2-2.4 × 1.2-2 mm, apex obtuse to acute. Staminate scales ovate-lanceolate to ovate, 1.3-3.5 × 0.8-1.4 mm, base clavate, apex acute to obtuse. Anthers 0.6-1.5(-1.8) mm. Perigynia spreading to reflexed, green, 6-13-veined abaxially, (0-)1-12-veined adaxially over achene, broadly ovate to suborbicular, cuneate or concavely tapered from widest point to beak, 1.9-3.8 × (1.3-)2.1-3 mm, 1.1-1.7(-1.9) times as long as wide; beak 0.45-1.25 mm, 0.23-0.5(-0.63) length of body, serrulate, teeth 0.15-0.45 mm. Achenes deltate to rhombic-orbiculate, 1-1.9 × 1-1.7 mm.
Very much like no. 54 [Carex interior L. H. Bailey]; stems scabrous on the angles above; lvs 0.5-4 mm wide; perigynia green, seldom castaneous, usually evidently several-nerved ventrally, 1.9-3.8 נ1.3-3 mm, 1.1-1.7 times as long as wide, broadly ovate to suborbicular, cuneately or somewhat concavely narrowed from the widest point to the sparsely and less conspicuously serrulate, sharply bidentate beak 0.5-1.2 mm. Swamps and bogs; N.S. to Fla., especially on the coastal plain, but also w. to Mich., Ill., Mo., Ark., and Tex. Var. atlantica, with nearly the range of the species, is relatively robust, with the widest lvs 1.5-4 mm, the infl mostly 1.8-4.5 cm, with 3-8 spikes, and the perigynia 2.3-3.8 ױ.5-3 mm. (C. incomperta) Var. capillacea (L. H. Bailey) Cronquist, mainly on the coastal plain, but also occasionally inland to O., s. Ont., s. Mich., and n. Ind., is smaller and more slender, with lvs 0.5-1.5 mm wide, the infl 0.8-2 cm with 2-5 spikes, the perigynia 1.9-3 נ1.3-2 mm. (C. howei)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.