Description from Flora of China
Panicum submontanum Hayata.
Perennial. Culms rambling, often rooting at lower nodes, 1–2 m long, branched, terete, subglabrous to puberulous, nodes glabrous or puberulous. Leaves cauline; leaf sheaths loose, striate, puberulous; leaf blades narrowly lanceolate, 10–25 × 1–2 cm, pilose, base abruptly narrowed, apex acuminate; ligule ca. 1 mm, ciliate. Panicle oblong to ovate in outline, 10–23 cm, the axis puberulous, much branched; branches tangled, viscid. Spikelets ovate, 1.5–2 mm, sparsely puberulous to glabrous; lower glume ovate, 2/3–3/4 length of spikelet, 3–5-veined; upper glume as long as spikelet, 5-veined; lower lemma similar to upper glume, palea well developed; upper floret as long as spikelet, pale brown, smooth, shiny. Fl. and fr. Jul–Mar. 2n = 36.
Forest shade. Fujian, Guangdong, Guangxi, Jiangxi, Taiwan, Yunnan [Bhutan, India, Indonesia, Malaysia, Myanmar, New Guinea, Philippines, Thailand, Vietnam; Australia].