2. Hemarthria vaginata Buse in Miquel, Pl. Jungh. 3: 14. Feb 1854 [preprint]; 3: 354. Aug 1854.
具鞘牛鞭草 ju qiao niu bian cao
Hemarthria protensa Nees ex Steudel; Manisuris protensa (Nees ex Steudel) Hitchcock; Rottboellia protensa (Nees ex Steudel) Hackel; R. vaginata (Buse) Backer.
Perennial. Culms loosely tufted, stout, ascending or sometimes decumbent and rooting from lower nodes, 20–80 cm tall, nodes conspicuous, dark, glabrous or pilose. Leaf sheaths rather loose, compressed, keeled, longer than internodes; leaf blades linear, 1–20 × 0.3–0.8 cm, soft, glabrous, base subcordate; ligule 0.5–2 mm. Racemes solitary or fascicled, 6–18 cm, articulation line oblique, not disarticulating. Sessile spikelet somewhat longer than adjacent internode, 6–11 mm; callus acute, 1.5–4 mm; lower glume narrowly lanceolate, leathery, flat on back, smooth, evenly tapering to an acuminate, usually minutely emarginate apex; upper glume adnate to rachis, 5–7 mm, acuminate-aristate; lower floret 3–5 mm; upper floret ca. 3 mm, palea linear, ca. 2 mm; anthers 1.2–1.3 mm. Pedicelled spikelet 7–12 mm, lower glume smooth on upper edges, long-acuminate, upper glume caudate-aristate. Fl. and fr. autumn. 2n = 54.
Field margins, open wet places; below 500 m. Guangdong, Guangxi, Guizhou, S Yunnan [Bangladesh, Bhutan, NE India, Indonesia, Myanmar, Nepal, Thailand, Vietnam].