Plants densely cespitose. Culms dark brown to chestnut at base, surrounded by remains of previous year’s leaf bases, but not conspicuously fibrillose; flowering stems 60–180 cm × 2–2.5 mm, much longer than leaves at maturity, glabrous. Leaves: sheaths glabrous, ivory to brown on back, dark chestnut-hyaline on front, sometimes finely red dotted near apex; blades rigid, flat distally but often keeled or channeled near base, margins revolute, 4–8 mm wide, finely retrorse-scabrous adaxially, margins and abaxial midribs also sometimes finely scabrous. Inflorescences: peduncles of lateral spikes slender, to 10 mm, finely scabrous; peduncle of terminal spike scabrous; proximal bracts shorter than inflorescences; sheaths 9–100 mm; blades 2–3.5 mm wide. Lateral spikes 6–15, 1–3 per node; proximal spikes well separated (except those at same node), erect or arching at maturity, pistillate with 15–45 perigynia attached less than 1 mm apart, cylindric, 2.5–8 × 4–6 mm; distal spikes staminate or androgynous, erect, crowded near apex, sessile or short-pedunculate. Terminal spike staminate, often crowded with other staminate or predominantly lateral staminate spikes, 20–80 × 2.5–7 mm. Pistillate scales suffused with chestnut except for hyaline margins and green midrib, ovate to oblong, shorter than mature perigynia, apex acute, sometimes with scabrous awn to 1 mm, glabrous. Perigynia green, usually red dotted, strongly 2-ribbed, 12–20-veined, loosely enveloping achene, lance-ellipsoid, 5–8 × 1.4–2.7 mm, membranous, base with short stipe, apex tapering to beak, shortly and evenly pubescent; beak bidentate, margins serrulate. Achenes sessile, 3–4 × 1.4–2.2 mm.
