Plants densely cespitose. Culms 40-100 cm; vegetative culms conspicuous, with spreading leaf blades evenly along stem. Leaves: sheaths adaxially green-veined to within 3 mm of collar, adaxially firm, summits usually brown tinged, U- or V-shaped, thick; distal ligules to 2 mm; blades 7-12 per fertile culm, 12-25 cm × 3-5 mm. Inflorescences open at least proximally, brown, (4-)5-9 cm × 10-20 mm; proximal internode (4-)5-15 mm; 2d internode (3-)5-11 mm; proximal bracts scalelike. Spikes 5-12, distant, distinct, lanceoloid, 12-28 × 3.5-7 mm, bases tapered, apex acute. Pistillate scales white-hyaline or pale brown with pale brown midstripe, oblong-ovate, 4-5 mm, 1/2 length of and narrower than perigynia, apex acute. Perigynia appressed-erect, pale brown, conspicuously 5-7-veined abaxially, conspicuously 3-7-veined adaxially, lanceolate, flat to plano-convex, 6-9 × (1.5-) 2-2.5 mm, 0.3 mm thick, margin flat, including wing 0.2-0.4 mm wide; beak tip flat, ciliate-serrulate, abaxial suture inconspicuous, distance from beak tip to achene 3.1-4.5 mm. Achenes elongate-oblong, 2-2.7 × 0.8-0.9 mm, 0.3 mm thick. 2n = 80.

Fruiting early-mid summer. Moist to wet, deciduous flood plains, lowland woods, and thickets; 100-400 m; Ont.; Ark., Ill., Ind., Iowa, Kans., Ky., Mich., Minn., Mo., Ohio, Okla., Tenn., Wis.

Frequent in low wet places in woods where it often forms extensive and pure stands if not obstructed by undergrowth. Occasional in buttonbush swamps and wet woods and on flood plains. Northward it is usually found with bur oak.

Cespitose, with numerous very leafy sterile stems; fertile stems stout, 5-10 dm; main lvs 3-5 mm wide; sheaths ventrally green-veined almost to the summit; spikes 5-10, gynaecandrous, fusiform, pointed at both ends, 15-25 נ4-6 mm, closely aggregated into a dense cluster 4-8 cm; pistillate scales lanceolate, half as long as the perigynia, pale brown with hyaline margins; perigynia appressed, lanceolate, thin, 6.5-10 mm, 3-4 times as long as wide, finely nerved on both sides, gradually tapering to the flat, serrulate, deeply bidentate beak half as long as the body; achene lenticular, 2-2.5 mm, less than 1 mm wide. Low woods, wet meadows, and river-bottomlands; O. and Ky. to Mich., Minn., Man., Kans., and Okla.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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