Plants densely cespitose. Culms 35-100 cm. Leaves: sheaths adaxially green-veined nearly to collar, narrow hyaline band or sharp Y-shaped region at collar, adaxially firm, summits U-shaped; distal ligules 1.5-4.5 mm; blades 3-4 per fertile culm, 15-30 cm × 1.5-3 mm. Inflorescences nodding, open, yellow-brown to reddish brown, 3.5-8 cm × 5-14 mm; proximal internode 5-18 mm; 2d internode 5-17 mm; proximal bracts scalelike with bristle tips shorter than inflorescences. Spikes 3-7, distant, distinct, globose, (6-)9-14 × 6-9 mm, base usually attenuate, apex rounded; lateral spikes with staminate portion 2-6 mm at base. Pistillate scales reddish brown, with green or pale midstripe, lanceolate, 2.5-3 mm, shorter or longer and narrower than perigynia, margin reddish brown, apex firm, acuminate or awned to 0.8 mm. Staminate scales with reddish brown margins. Perigynia widely spreading, reddish brown, conspicuously 5-veined or more on each face, ± orbiculate, flat except over achene, 4-5.6 × 1.8-2.8 mm, 0.4-0.5 mm thick, base rounded, margin flat, including wing 0.6-0.9 mm wide; beak widely spreading, pale to reddish brown at tip, flat, ciliate-serrulate, abaxial suture with golden brown margin, distance from beak tip to achene 2-3 mm. Achenes elliptic, 1.5-1.8 × 0.8-1 mm, 0.3-0.4 mm thick. 2n = 74. Fruiting early summer. Freshwater marshes, shores, and swales, wet woods, in sandy or peaty, acidic soils; 0-400 m; Conn., Del., D.C., Ill., Ind., Ky., Md., Mass., Mich., Mo., N.J., N.Y., N.C., Ohio, Pa., R.I., Va., W.Va., Wis. The distribution of Carex straminea is discontinuous: scattered occurrences or clusters of occurrences are widely separated from each other.