Asian Crab Grass

Annual. culms decumbent, rooting at lower nodes, 30–60 cm tall. Leaf sheaths glabrous or lower sheaths papillose-pilose; leaf blades linear, 2.5–15 × 0.2–0.9 mm, usually scabrid on both surfaces, rarely sparsely pilose; ligule 1–3.5 mm. Inflorescence digitate or subdigitate; racemes 2–5, 4–14 cm; spikelets paired, imbricate; rachis triquetrous, ca. 1 mm wide, winged. Spikelets lanceolate, ca. 3 mm, those of a pair usually different; lower spikelet glabrous, upper spikelet pubescent; lower glume very small, almost absent or up to 0.4 mm, triangular or bifid, veinless; upper glume lanceolate, ca. 2/3 length of spikelet, 3-veined, pilose; lower lemma as long as spikelet, 7-veined, lower spikelet with equidistant veins, upper spikelet with wider glabrous interspaces on either side of midvein, lateral veins crowded near margins, rows of silky hairs between lateral veins, usually also setose, the hairs spreading halo-like at maturity; upper lemma yellowish, slightly shorter than spikelet. Fl. and fr. May–Sep. 2n = 54, 72.

Fujian, Hainan, Yunnan [India, Indonesia, Malaysia, Myanmar, New Guinea, Sri Lanka, Thailand; Africa, Australia; introduced in America].

Waste ground, often on sand, including seashore sand; below 2000 m.

Paspalum bicorne Lamarck, Tabl. Encycl. 1: 176. 1791; Digitaria biformis Willdenow; Panicum bicorne (Lamarck) Kunth; P. biforme (Willdenow) Kunth.