Plants annual; rhizomes 1 mm diam. Culms cylindric, ridged when dry, 0.05–0.5 m × 0.5–1 mm. Leaves 3–4, 1 cauline, nearly equaling culm; sheaths disintegrating to fibers; blades 1–2, thickly C-shaped in cross section, distally flat, from much shorter to ca. 1/2 as long as sheath, 0–200 × 0.2–1 mm, smooth or margins distally spinulose. Inflorescences capitate or of 1 spikelet or rarely with 1 or 2 branches to 3 cm; proximal bract erect, resembling leaf blades, 5–200 mm. Spikelets 1–10, 5–13 × 2–3 mm; scales straw-colored or often flanks distally bright orange-brown, central region often greenish, ovate, 2.5–3.4(–5) × 1.5 mm, smooth or awn sparsely spinulose, margins ciliolate, midrib keeled distally, apex acute, awn 0.2–0.3 mm or to 2 mm on proximal scale. Flowers: perianth absent; anthers 0.5 mm; styles 2-fid or rarely few 3-fid. Spikelet achenes blackish brown when ripe, unequally biconvex to obscurely trigonous, adaxial surface longitudinally convex and horizontally concave with a convex center, ovoid to obovoid, 1–1.6 × 1–1.5 mm, with 12–15 sharp to blunt ridges; beak 0.1 mm. Amphicarpic achenes thickly trigonous with rounded abaxial faces, ellipsoid, prominently beaked, 2.2–3.2 mm, rugose. 2n = 10.
