热带鼠尾粟 re dai shu wei su

Panicum tenuissimum Martius ex Schrank, Denkschr. Königl.-Baier. Bot. Ges. Regensburg 2: 26. 1822.

Annual, delicate. Culms tufted, weak, 20–100 cm tall. Leaf sheaths glabrous; leaf blades linear, flat or folded, 5–20 × 0.2–0.5 cm, glabrous; ligule 0.2–0.3 mm. Panicle narrowly oblong, open, diffuse, 10–40 × 2–6 cm; lowest primary branches single or paired, branches capillary, lower 1/2 bare, secondary branches spreading. Spikelets gray or purplish, 0.8–1 mm, gaping at maturity; lower glume oblong, 0.1–0.4 mm, truncate-erose; upper glume ovate-oblong, 0.3–0.5 mm, subacute; lemma ovate, as long as spikelet, acute to obtuse. Anthers 3, 0.1–0.3 mm. Grain obovate. 0.4–0.7 mm, truncate. 2n = 12.

Disturbed or cultivated places at low elevations, introduced. S Taiwan [native to tropical America; now widely adventive in warm parts of the world].