筒轴茅 tong zhou mao

Stegosia cochinchinensis Loureiro, Fl. Cochinch. 51. 1790; Rottboellia exaltata Linnaeus f. (1781), not (Linnaeus) Linnaeus f. (1779).

Coarse annual. Culms stout, 1–3 m tall, 5–10 mm in diam., supported below by stilt roots, branched in upper part. Leaf sheaths tuberculate-hispid with stiff irritant hairs or sometimes glabrescent; leaf blades linear-lanceolate, 20–50 × 0.5–2.5 cm, glabrous or adaxial surface hispidulous, very scabrid along margins, midrib broad, white, apex acuminate; ligule a ciliate membrane, ca. 1 mm. Racemes yellow and green, 6–15 × 0.25–0.4 cm, stiff, terminating in a green tail of reduced spikelets; rachis internodes 4–6 mm, rounded on back, slightly longer than adjacent pedicel. Sessile spikelet pale yellow, 5–6 mm; lower glume ovate, minutely scaberulous on back, keeled only toward entire or very minutely 2–3-toothed apex; lower lemma as long as upper lemma. Pedicelled spikelet green, variable, 3–5 mm, narrowly ovate, herbaceous. Fl. and fr. Jul–Oct.

Sunny or moderately shady localities, roadsides, hill thickets, dry cultivated fields, grasslands; below 1900 m. Fujian, Guangdong, Guang-xi, Guizhou, Hainan, Hunan, Sichuan, Taiwan, Yunnan, Zhejiang [throughout the Old World tropics; introduced to the Caribbean].