Plants cespitose; rhizomes long. Culms trigonous in cross section, 30-85 cm, scabrous angled distally. Leaves: basal sheaths reddish purple; ligules as wide as to longer than wide; blades light green, glabrous, flat to W-shaped, widest leaves 1.8-4.3(-5) mm wide. Inflorescences 8-30 cm; proximal bract (3-)9-35 cm, mostly equaling or exceeding inflorescence; proximal 1-3 spikes pistillate, erect or, sometimes, the proximal spreading, cylindric; terminal 1-3 spikes staminate. Pistillate scales narrowly ovate, 3.5-5.2 × 1.1-2.1 mm, shorter than perigynia, margins entire, apex obtuse to acute, awnless. Perigynia ascending to spreading, often green or straw colored, strongly 9-12-veined, veins running into beak, lance-ovate, 5.9-10.2 × 2.4-3.3 mm, apex contracted; beak 2.4-4.2(-4.8) mm, bidentate, finely scabrous at least near tip and on teeth, teeth straight, to 0.5-1.4 mm. Stigmas 3. Achenes brown, symmetric, not indented, trigonous, smooth.

Fruiting May-Aug. Acidic soil of bogs and boggy meadows, open swamp forests, peaty or sandy pond and lakeshores, seeps; 0-1100 m; N.S.; Ark., Conn., Del., Ga., Maine, Md., Mass., N.J., N.Y., N.C., R.I., Tenn., Va.