Description from Flora of China
Panicum punctatum N. L. Burman, Fl. Indica 26. 1768; P. mucronatum Roth ex Roemer & Schultes; Paspalidium mucronatum (Roth ex Roemer & Schultes) Ohwi; Paspalum aquaticum Masamune & Syozi; P. punctatum (N. L. Burman) Stapf ex Ridley (1925), not (Linnaeus) Flüggé (1810); Setaria punctata (N. L. Burman) Veldkamp.
Perennial. Culms stout, spongy, trailing and rooting at the lower nodes, flowering shoots 50–100 cm or more tall. Leaf sheaths dilated, smooth, margins membranous; leaf blades linear-lanceolate, 10–25 × 0.3–0.8 cm, scabrous, adaxial surface papillose, apex acuminate; ligule 1–2 mm. Inflorescence axis 10–30 cm; racemes 8–15, 1–5 cm, overlapping at least in upper part of inflorescence; rachis 0.5–1.5 mm wide, undulate, apex acicular. Spikelets ovate-oblong, 2–3 mm; lower glume cufflike, 1/4 as long as spikelet, truncate; upper glume suborbicular, 1/4–1/2 as long as spikelet, 3–5-veined, rounded or truncate; lower floret neuter, lemma ovate, as long as or slightly shorter than upper floret, prominently 3–5-veined, acute, palea absent; upper lemma ovate, finely rugose, cuspidate-acuminate. Fl. and fr. Jul–Oct.
Floating in fresh water, rooting along marshy streamsides, in wet soil; 100–500 m. Fujian, Guangdong, Hainan, Taiwan [Bangladesh, Cambodia, India, Indonesia, Laos, Malaysia, Myanmar, Philippines, Thailand, Vietnam; E Africa].