Culms 25-80 cm, glabrescent. Leaves: sheaths pilose; ligules as long as or shorter than wide; blades 1.5-4 mm wide, glabrescent or pilose abaxially and/or proximally. Inflorescences: lateral spikes usually approximate, 7-18 × 3.5-5 mm; terminal spike gynecandrous, at least 1/2 of flowers pistillate, 12-25 mm. Pistillate scales ovate, 1.5-2.4(-3) × 0.7-1.5 mm, shorter than perigynia, apex acute to acuminate. Staminate scales oblong-ovate, 2.4-5.1 mm, apex acuminate. Anthers 1.4-2.5 mm. Perigynia spreading, 7-14-veined, obovate-circular, nearly circular in cross section, 2.1-3 × 1.1-2 mm, not papillose, glabrous or sparsely pilose; beak absent. Achenes 1.6-2.2 × 1-1.4 mm. 2n = 48. Fruiting late spring-early summer. Ditches, shores; 0-500 m; Ark., Del., D.C., Ga., Ind., Kans., Md., Miss., Mo., N.J., N.C., Ohio, Okla., Pa., Tenn., Tex., Va., W.Va.
Tufted, 3-8 dm, tinged with red-purple at base; lf-sheaths glabrous or hairy on the back, glabrous or nearly so ventrally; blades elongate, 2-4 mm wide, glabrous except at base; spikes usually 3, ±approximate, short-cylindric or narrowly ovoid, 1-2 cm, densely fld, the terminal one pistillate above, the others wholly pistillate; pistillate scales ovate, usually much shorter than the perigynia, brown-tinged, acute or short-cuspidate; perigynia obovoid, 2.2-2.8 mm, two-thirds as wide and nearly as thick as wide, turgid, spreading, strongly nerved, minutely beaked; achene concavely trigonous, bent-apiculate. Dry woods and meadows; N.J. and Pa. to O., Mo., and Okla., s. to N.C. and Tex.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.