Plants mat-forming; rhizomes to 1 mm diam; terminal tubers sometimes present, to 3 mm thick, fleshy. Culms subcylindric, 0.2–1.5 m × 0.5–1 mm. Leaves 3–20+, smooth; sheath fronts sometimes delicately pinnate-fibrillose; blades 3–20, when erect C-shaped in cross section proximally, elliptic most of length, when submerged usually flaccid and filiform to narrowly ribbonlike, probably longer than sheath, 0.2–1 mm wide. Inflorescences a solitary, erect spikelet; proximal bract erect, like stiff leaf blade, 7–60 mm. Spikelets 5–15 × 3–7 mm; scales pale brown, or central region green when young, ovate-lanceolate, 4–6 × 1.5 mm, smooth, margins sometimes ciliolate apically at 40X, midrib obscure, apex acute, entire, minutely mucronate. Flowers: perianth members 6, brown, bristlelike, from 1/2 of to equaling achene beak, spinulose; anthers 2–3.5 mm; styles 3-fid. Achenes brown, strongly trigonous, obovoid to obpyriform, (2.5–)3–3.5 × 1.5–1.7 mm; beak 0.3–0.8 mm. 2n = 72.
