Culms 20-75 cm, glabrescent. Leaves: sheaths sparsely pilose, but usually densely pilose at mouth; ligules shorter than wide; blades 1.5-4 mm wide, glabrescent, or often persistently pilose proximally. Inflorescences: lateral spikes approximate or proximal distant, 6-15 × 4-5 mm; terminal spike gynecandrous, at least 1/2 of flowers pistillate, 14-25 mm. Pistillate scales ovate, 1.9-3(-3.5) × (0.8-)0.9-1.5(-1.7) mm, shorter than to equaling perigynia, apex acute to acuminate, sometimes with awn to 0.5 mm. Staminate scales oblong-obovate, 2.7-5.3 mm, apex acuminate or short-awned. Anthers 1.5-2.2 mm. Perigynia ascending, 5-18-veined, obovate-circular, ± trigonous in cross section, 2-3.5 × 1.1-2.1 mm, not papillose, glabrous or sparsely pilose; beak absent. Achenes 1.6-2.3 × 0.9-1.5 mm. Fruiting late spring-early summer. Dry open woods, neutral to acidic soils; 0-500 m; Ala., Ark., Del., D.C., Fla., Ga., Iowa, La., Md., Miss., Mo., N.J., N.C., S.C., Tenn., Tex., Va.; Mexico.
Tufted, red-purple at base; main lvs erect, equaling the stems, 2-4 mm wide; spikes 2-5, usually 3, the terminal one pistillate above; pistillate spikes approximate, short-cylindric or narrowly ovoid, 8-15 mm, sessile or nearly so; lowest bract elongate, much surpassing the spikes, the others small; anthers 1.3-2 mm; pistillate scales usually much shorter than the perigynia, the body with brownish hyaline margins, acute to short-cuspidate; perigynia flattened-obovoid, 2-2.8 ױ.3-2 mm, appressed-ascending, 2-ribbed, rounded at the beakless tip. Dry woods and fields; Me. to Fla., w. to Mich., Io., Tex., and Mex. Var. complanata, with glabrous blades and glabrous to hairy sheaths, the perigynia usually nerveless ventrally, occurs on the coastal plain from N.J. s. Var. hirsuta (L. H. Bailey) Gleason, with soft-hairy blades and sheaths, the perigynia with fine but distinct nerves on both sides, occurs nearly throughout the range of the sp. (C. hirsutella)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.