Description from Flora of China
Panicum paludosum Roxburgh.
Aquatic annual or rhizomatous perennial. Culms geniculately ascending, rooting at lower nodes, branching, succulent, 30–110 cm tall, upper nodes glabrous, often conspicuous. Leaves cauline; leaf sheaths striate, glabrous, lower sheaths often inflated; leaf blades linear, flat, 7–35 × 0.5–1 cm, glabrous, scabrid, base straight or subcordate, apex acute; ligule 1–2 mm, a ciliate membrane. Panicle terminal or axillary, pyramidal when fully exserted, 10–20 cm, much branched; branches glabrous, scabrid, secondary and tertiary branches often appressed. Spikelets lanceolate to narrowly ovate, 3–4 mm, glabrous, acuminate; lower glume broadly ovate, 1/6–1/3 length of spikelet, clasping at the base of the spikelet, membranous, 0–1-veined, obtuse to acute; upper glume as long as spikelet, 7–9-veined; lower lemma similar to upper glume, palea absent or present and well developed; upper floret 2/3 length of spikelet, green or pale yellow, smooth, shiny. Fl. and fr. Jun–Oct.
Shallow waters, swampy places. Fujian, Guangdong, Guangxi, Taiwan, Yunnan [India, Malaysia; tropics of the New World].