Description from Flora of China
Panicum assamicum J. D. Hooker, Fl. Brit. India 7: 40. 1896 ["1897"].
Culms decumbent, 50–70 cm tall, ca. 5 mm in diam., nodes many, brown, glabrous. Leaf sheaths with one margin tuberculate-ciliate; leaf blades linear-lanceolate, 10–20 × 0.4–1.2 cm, a few setae at base above ligule, base rounded, apex acuminate; ligule 0.3–0.5 mm. Panicle narrow, dense, pale green, 8–18 × 1–3 cm; branches 1–4 cm, appressed to rachis with tightly clustered spikelets; rachis scabrous, narrowly winged; pedicels 0.2–0.8 mm, scabrous. Spikelets lanceolate, 3–3.2 × ca. 1 mm, veins scabrous toward apex, otherwise smooth, glumes and lower lemma not separated; lower glume broadly ovate, 1/3 spikelet length, 1–5-veined, acute; upper glume slightly shorter or as long as lower lemma, 5-veined, nearly smooth, sharply acute; lower lemma as long as spikelet, sharply acute; upper lemma ca. 2.5 mm, margins flat for most of their length or only toward apex, apex acute. Fl. and fr. Jul–Oct.
Streams. Guangdong, Guangxi, Hainan, Yunnan [NE India, Thailand].