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.
Densely tufted, aphyllopodic, 4-10 dm; main lvs 2-3 mm wide, shorter than the stem, their sheaths ventrally green-veined almost to the summit, with only a short hyaline area; spikes 4-8, gynaecandrous, sessile, well separated in an infl 3-6 cm, or the uppermost aggregated, the pistillate part short-ovoid or subglobose, 7-10 mm, often with an elongate staminate base; pistillate scales lanceolate, much narrower and somewhat shorter than the perigynia, hyaline or nearly so, brown-tinged with a paler midnerve,
acuminate to shortly aristate; perigynia very flat and thin, lightly but sharply nerved on both faces, the flattened, serrulate beak half as long as the body; achene lenticular, 1.5 נ0.75 mm. Var. straminea, of nonsaline swamps and wet meadows, from Mass. to D.C., w. to Mich. and Ind., has the perigynia 4-5.2 mm, half to two-thirds as wide, broadest at a third to two-fifths of their length, the body ovate to orbicular. (C. richii) Var. invisa W. Boott, of salt marshes from Nf. to Va., has the perigynia 4.2-5.5 mm, two-fifths or three-fifths as wide, broadest at two-fifths to half of their length, the body orbicular to obovate. (C. hormathodes)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.