Description from Flora of China
Annuals. Roots fibrous. Culms tufted, 5-35 cm tall, ± slender, triquetrous, smooth, base with leaves. Leaves shorter than or sometimes equaling culm; sheath purplish brown; leaf blade 1.5-4 mm wide, flat, sometimes slightly plicate. Involucral bracts 3-5, leaflike, longer than inflorescence. Inflorescence a simple anthela; rays 2-7, 0.8-5 cm, each with 1 spike. Spike broadly ovoid to in outline subflabelliform, with 3-10 spikelets; rachis 2-5 mm. Spikelets densely and nearly digitately arranged, narrowly linear-ovoid, 1-2.5(-4) cm × 3-4 mm, basal ones spreading and apical ones obliquely spreading, 10-20-flowered; rachilla wings white, narrow, hyaline. Glumes pale to straw-colored on both surfaces and sometimes with rusty brown striae but middle green, tightly imbricate, ovate, 3-3.5 mm, thinly leathery, strongly folded, 9-13-veined, keeled, apex acute and with a straight and slightly long mucro. Stamens 3; anthers linear, 0.6-0.7 mm; connective apex reddish, ovate, ca. 0.1 mm. Style 0.9-1.3 mm; stigmas 3, 0.5-0.8 mm. Nutlet dark brown, obovoid, ca. 1/3 as long as subtending glume, 3-sided, slightly concave on 3 sides, puncticulate. Fl. and fr. Jul-Dec. 2n = ca. 98, 112, 114, 128.
Grasslands, seashores, along trails, lake margins, forests, stony clefts, wet sandy riverbanks, open fields, paddy field margins; near sea level to 900(-1600) m. Anhui, Chongqing, Fujian, S Gansu, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Liaoning, Nansha Qundao, Shandong, Shanxi, Sichuan, Taiwan, Xisha Qundao, Xizang, Yunnan, Zhejiang [Afghanistan, Bangladesh, Bhutan, India, Indonesia, Japan, Kashmir, Laos, Myanmar, Nepal, Pakistan, Papua New Guinea, Philippines, Sri Lanka, Thailand, Vietnam; Africa, Australia, Central, North, and South America, Indian Ocean islands, Madagascar, Pacific Ocean islands].