Plants perennial, mat-forming; rhizomes evident, long, 1–2 mm thick, firm, cortex persistent, longer internodes 10–55 mm, scales often fugaceous, 5–10 mm, membranous, not fibrous. Culms terete to markedly compressed, to 3 times wider than thick, often with to 25 blunt ridges when dry, 10–100 cm × 0.5–2.5(–3.5) mm, firm (to soft), internally spongy. Leaves: distal leaf sheaths persistent, rarely splitting abaxially, proximally mostly red, distally green (or red), papery (to membranous), apex truncate to obtuse, tooth sometimes present on some or all culms, 0.1–0.6(–1) mm. Spikelets narrowly lanceoloid to ovoid, 5–40 × 2–5 mm, acute, rarely obtuse; proximal scale clasping (2/3–)3/4 or more of culm to amplexicaulous, usually variably in same plant; subproximal scale empty or with flower, usually empty in some spikelets and with flower in other spikelets in same plant; floral scales deciduous, often spreading in fruit, 30–80, 3–5 per mm of rachilla, medium brown, sometimes red-brown or dark chestnut-brown, midrib regions often stramineous to green, ovate to narrowly lanceolate, 2.5–5.5 × 1.5–2.5 mm, entire, mostly carinate in distal part of spikelet. Flowers: perianth bristles 4(–5), sometimes rudimentary or absent, brown, slender to stout, much shorter than achene to equaling tubercle; stamens 3; anthers dark yellow to orange-brown, 1.3–2.7 mm; styles 2-fid. Achenes not persistent, yellow maturing to yellow-brown or dark brown, ellipsoid, obovoid, or obpyriform, biconvex to plano-convex, angles obscure, 1.1–1.9 × 0.8–1.5 mm, apex rounded, neck absent or short, smooth at 30X, or finely rugulose at 10–20X with 20 or more horizontal ridges in a vertical series. Tubercles brown to whitish, pyramidal, as high as or sometimes much higher than wide, 0.35–0.7 × 0.25–0.7 mm. 2n = 18, 19, 38.
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