Description from Flora of China
Panicum semiundulatum Hochstetter ex A. Richard, Tent. Fl. Abyss. 2: 364. 1851.
Annual. Culms loosely tufted, slender, decumbent at base, rooting at lower nodes, 20–50 cm tall. Leaf sheaths pubescent; leaf blades ovate-lanceolate, 1–3 × 0.1–0.8 cm, both surfaces densely pubescent, margins cartilaginous, crinkled-serrate; ligule ciliate. Inflorescence axis 2–7 cm; racemes 5–8, 0.5–2 cm, ascending; rachis triquetrous, setose; spikelets single, in neat 2 rows, overlapping. Spikelets ovate, plump, strongly gibbous on abaxial side, flat on adaxial side, 1.5–2 mm, glabrous to pubescent, subacute; lower glume 1/3–2/5 spikelet length, 3-veined; upper glume 4/5 spikelet length, 5-veined; upper lemma swollen, striate, transversely rugulose, apex acute. Fl. and fr. Jul–Oct.
Mountain slopes, fields. Hainan, Yunnan [tropical Africa, S Asia].