15. Eragrostis ferruginea (Thunberg) P. Beauvois, Ess. Agrostogr. 71. 1812.
知风草 zhi feng cao
Poa ferruginea Thunberg in Murray, Syst. Veg., ed. 14, 114. 1784; Eragrostis mairei Hackel; E. mairei var. eglandis B. S. Sun & S. Wang.
Perennial. Culms single or tufted, erect or geniculate at base, 30–110 cm tall, 2–4 mm in diam. Leaf sheaths laterally compressed, glabrous but along margins and summit densely pilose, sometimes glandular along main vein; ligules a line of hairs, ca. 1 mm; leaf blades linear-lanceolate, (4–)20–40 × 2–6 mm, glabrous or adaxial surface sparingly covered with silky hairs on basal part. Panicle large and open, 15–40 × 4–15 cm, 1–3-branched at each node, glabrous in axils; branchlet and pedicel usually glandular at middle or above middle. Spikelets oblong, purplish black, gray-green, rarely yellowish green, 5–10 × 2–2.5 mm, (4–)7–12-flowered. Glumes lanceolate, open, 1-veined, apex acuminate, lower glume 1.4–2 mm, upper glume 2–3 mm. Lemma ovate-lanceolate to oblong, 2.4–3 mm, apex obtuse, lower lemma ca. 3 mm. Palea persistent, along keels ciliolate. Anthers ca. 1 mm. Caryopsis rectangular-prismatic with a shallow, narrow adaxial groove, laterally compressed, faintly striate, reddish brown, 0.7–1.5 mm. Fl. and fr. Aug–Dec. 2n = 80.
Mountain slopes, roadsides. Anhui, Beijing, Fujian, Guizhou, Henan, Hubei, Shaanxi, Shandong, Taiwan, Xizang, Yunnan, Zhejiang [Bhutan, India (Sikkim), Japan, Korea, Laos, Nepal, Vietnam].
The name "Eragrostis ferruginea var. yunnanensis Keng" (Claves Gen. Sp. Gram. Prim. Sin. 178. 1957) was not validly published bcause no Latin description was provided.