Description from Flora of China
Agrostis fertilis Steudel, Syn. Pl. Glumac. 1: 170. 1854; Sporobolus elongatus R. Brown var. purpureosuffusus Ohwi; S. fertilis (Steudel) Clayton var. purpureosuffusus (Ohwi) P. C. Keng & X. S. Shen; S. indicus (Linnaeus) R. Brown subsp. purpureosuffusus (Ohwi) T. Koyama; S. indicus var. major (Buse) Baaijens; S. indicus var. purpureosuffusus (Ohwi) T. Koyama.
Perennial. Culms densely tufted, erect, rigid, 25–100(–120) cm tall. Leaf sheaths glabrous but margin ciliolate, basal sheaths papery, lightly keeled; leaf blades linear, flat or involute, 15–50(–65) × 0.2–0.5 cm, glabrous or adaxial surface thinly pilose, tapering to a long filiform apex; ligule ca. 0.5 mm. Panicle linear, contracted to spikelike, often interrupted especially at base, 7–45 × 0.5–1.5 cm; branches 1–2.5(–5) cm, erect and appressed to main axis, or looser and narrowly ascending, densely spiculate throughout. Spikelets grayish or yellowish green, 1.7–2 mm; lower glume oblong, ca. 0.5 mm, veinless, apex truncate-erose; upper glume oblong-elliptic, 1/2–2/3 spikelet length, 1-veined, ± acute; lemma ovate, as long as spikelet, indistinctly 1(–3)-veined, acute. Anthers 3, 0.8–1 mm. Grain red-brown, obovate-elliptic, 0.9–1.2 mm, distinctly shorter than its lemma and palea, these gaping widely beyond its top, apex truncate. Fl. and fr. Mar–Dec. 2n = 36, 48, 54.
This common and variable, perennial weed is distinguished by its contracted panicle and short glumes. The spikelets are frequently infected by a black smut fungus.
Roadsides, field margins, grassy places on hill slopes, moist ground of mountain valleys. Anhui, Fujian, Gansu, Guangdong, Guizhou, Hainan, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Shandong, Sichuan, Taiwan, Xizang, Yunnan, Zhejiang [Bhutan, India, Indonesia, Japan, Malaysia, Myanmar, Nepal, Philippines, Sri Lanka, Thailand, Vietnam; occasionally introduced elsewhere].