Description from Flora of China
Annuals. Roots many, slender, fibrous. Culms densely tufted, 5-20 cm tall, flaccid, compressed 3-angled, smooth, few leaved basally. Leaves usually shorter than to sometimes equaling culm; sheath reddish brown to purplish brown, submembranous; leaf blade 1.5-2 mm wide, flat or folded. Involucral bracts 3-5, leaflike, several times as long as inflorescence, basally slightly widened. Inflorescences usually capitate, globose, 1-2 cm in diam., sometimes with a 1-2 cm ray, with many densely arranged spikelets. Spikelets narrowly oblong-ovoid to ovoid-oblong, 3-8 × 1.5-2 mm, compressed, 8-30-flowered; rachilla wings white, hyaline. Glumes white on both surfaces but sometimes sparsely rusty brown shortly striate, slightly spreading, broadly ovate, ca. 2 mm, hyaline, several veined, midvein green, apex mucronate. Stamens 2; anthers linear-oblong. Style elongate; stigmas 2. Nutlet yellowish brown, oblong, ca. 1 mm, plano-convex, sometimes nearly concave-convex. Fl. and fr. Aug-Sep.
Mountain slopes, along trails, sunny places in fields; below 100-1000 m. Anhui, Hebei, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Liaoning, Shandong, Shanxi, Zhejiang [Japan, Korea, Russia (Far East)].