Ann. Lyceum Nat. Hist. New York 1: 67. 1824.
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 oblongovate, 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.
Phenology: Fruiting late spring–early summer.
Habitat: Ditches, shores
Elevation: 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.