Plants perennial, mat-forming; rhizomes evident, fairly long to long, 0.5–2.5 mm thick, hard, cortex persistent, longer internodes 2–10 mm, scales persistent, sometimes decaying to coarse fibers, 5–10 mm, membranous to papery. Culms subterete to sometimes compressed, to (2–)3 times as wide as thick, often with (4–)5–10 ridges or angles, 5–90 cm × 0.3–0.8 mm, firm to soft, spongy. Leaves: distal leaf sheaths persistent, not splitting, proximally dark red, distally green to stramineous or red, thinly papery to membranous, apex usually red-brown, obtuse to subacute, often callose, tooth to 0.5 mm usually present on some culms. Spikelets ovoid, 3–8 × 2–3(–4) mm, apex obtuse (to acute); proximal scales amplexicaulous, apex entire; subproximal scale with a flower; floral scales spreading in fruit, 10–30, 5–7 per mm of rachilla, medium to very dark brown, midrib region often paler, ovate, 1.7–3 × 1–1.5 mm, apex rounded to obtuse (or acute), entire or shallowly notched (emarginate) or sometimes cut to 0.5(–0.7) mm deep, apical colorless hyaline part at least as wide as long, 0.2–0.7 mm, carinate in distal part of spikelet. Flowers: perianth bristles absent or rarely 1–3, pale brown, to 1/2 of achene length, sparsely retrorsely spinulose; stamens 3; anthers orange-brown, 0.8–1.7 mm; styles 3-fid or some 2-fid. Achenes persistent after scales fall, usually lemon yellow or dark yellow, orange, or medium brown, rarely greenish, obpyriform, nearly equilaterally to compressed-trigonous, often some biconvex, angles evident to prominent, 0.7–1.2 × 0.6–0.9 mm, neck short or absent, finely to coarsely rugulose at 10X, 12–20 horizontal ridges in vertical series, usually finely cancellate at 10–20X. Tubercles brown to whitish, greatly depressed, apiculate, sometimes pyramidal, 0.1–0.25 × 0.25–0.45 mm. 2n = 38.
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