Description from Flora of China
Annuals. Roots fibrous. Culms tufted, 2-12 cm tall, slightly soft, compressed triquetrous, winged at angles, smooth, base with leaves. Leaves shorter to longer than culm; sheath brownish, short; leaf blade 2-4 mm wide, flat, midvein abaxially slightly wing-shaped, margin smooth or sometimes spinulose. Involucral bracts 2-4, leaflike, longer than inflorescence. Inflorescence a simple or compound anthela; rays 4-7, mostly to 1.5 cm, sometimes short, each with 7-15 densely arranged spikelets. Spikelets at apex of rays, digitately arranged, linear-oblong to linear, 4-10 × ca. 1.8 mm, 12-30-flowered; rachilla straight, wingless, with successive glumes 0.5-0.7 mm apart. Glumes dark purple to blackish brown on both surfaces but middle yellowish green, lax, orbicular-ovate to suborbicular, ca. 1 mm but extended after anthesis, membranous, prominently longitudinally striate, 3-veined, apex rounded and mucronate. Stamens 2; anthers oblong; connective prominent beyond anthers. Style of medium length; stigmas 3. Nutlet at first yellowish but brownish when mature, ellipsoid to obovoid-ellipsoid, nearly as long as subtending glume, 3-sided, smooth, apex long mucronate. Fl. and fr. Sep-Oct.
Collections from Yunnan have a compound anthelate inflorescence, have nearly all spikelets solitary, and come from higher elevations than those from Sichuan. Further specimens might show that they merit taxonomic recognition.
● Wet places, shallow water; 1500-3000 m. N Sichuan, Yunnan.