Description from Flora of China
Annuals. Roots fibrous. Culms scattered, 30-60(-90) cm tall, stout, obtusely 3-angled, smooth, basally with leaves, base slightly swollen. Leaves few, shorter to slightly longer than culm; sheath reddish brown, long; leaf blade 4-8 mm wide, margin smooth. Involucral bracts 3 or 4, leaflike, longer than inflorescence. Inflorescence a compound anthela; rays 3-8, mostly to 12 cm, unequal in length; raylets lacking. Spikes subglobose, ellipsoid, or oblong, 1-3 × 0.6-1.7 cm, not pedunculate, with very many spikelets. Spikelets very densely arranged in several rows, narrowly linear-ovoid to linear, 5-10 × 1.5-2 mm, slightly compressed, 8-16-flowered; rachilla wings white, narrow, hyaline. Glumes reddish brown, lax, suboblong to oblong-lanceolate, ca. 2 mm, slightly spreading, veins very obscure, not keeled, margin involute, apex obtuse. Stamens 3; anthers short, oblong; connective prominent beyond anthers. Style slightly long; stigmas 3, ± short. Nutlet dark gray, narrowly oblong, ca. 1/2 as long as subtending glume, 3-sided, conspicuously reticulately striate. Fl. and fr. Jun-Oct.
Wet grasslands along trails, sandy soil at water margins, river margins, lake banks, paddy fields; 100-1300 m. Anhui, S Gansu, Hebei, Heilongjiang, Henan, Hubei, Jiangsu, Jilin, Liaoning, Nei Mongol, Ningxia, Shaanxi, Shandong, Shanxi, Zhejiang [Japan, Kashmir, Kazakhstan, Korea, Russia, Tajikistan, Uzbekistan; SW Asia, Europe].