大牛鞭草 da niu bian cao

Rottboellia altissima Poiret, Voy. Barbarie 2: 105. 1789; Hemarthria compressa (Linnaeus f.) R. Brown var. altissima (Poiret) Maire; H. compressa var. fasciculata (Hackel) Keng; Rottboellia compressa Linnaeus f. var. fasciculata Hackel; R. fasciculata Lamarck, nom. illeg. superfl.

Perennial, or sometimes annual. Culms loosely tufted to decumbent or stoloniferous, rooting at lower nodes, ascending up to 1.6 m tall, nodes glabrous. Leaf sheaths loose, compressed, keeled, usually shorter than internodes, glabrous except near mouth; leaf blades linear, 5–25 × 0.3–0.6 cm, acute; ligule ca. 0.3 mm. Racemes solitary or several per node, 5–10 cm, semicylindrical, articulation line oblique, tardily disarticulating. Sessile spikelet longer than adjacent internode, 5–7 mm; callus triangular, 0.8–2 mm; lower glume elliptic-oblong, leathery, flat on back, often with subapical constriction, apex obtuse to emarginate; upper glume papery, adnate to rachis, 4–7 mm, apex obtuse to acute; lower floret 3.5–5.2 mm; upper floret 3.2–4.6 mm. Pedicelled spikeletnarrowly lanceolate, lower glume acute, upper glume acuminate. 2n = 20, 36.

In or near water, damp places; 700–1900 m. Anhui, Beijing, Guizhou, Heilongjiang, Henan, Hubei, Shandong, Yunnan, Zhejiang [India, Indonesia, Myanmar, Thailand, Vietnam; Africa, SW Asia, Mediterranean region; introduced in America and New Zealand].

Hemarthria altissima occurs naturally mainly from the Mediterranean region through Africa, but there are scattered records from Asia and it is now widely naturalized in warm parts of America.