Asian Crabgrass

Perennials; culm stoloniferous, branching at lower nodes. Blade 5-15 cm long, 3-6 mm wide; sheath subcompressed; ligule membranaceous, ca. 2 mm long. Racemes 2, rarely 3, more than 15 cm long; rachis triangular, rigid, winged, axils hairy. Spikelet ca. 4 mm long, paired, pedicellate one villous, sessile one glabrous, rather far apart on rachis, lanceolate; lower glume veinless, ca. 0.7 mm long; upper glume lanceolate, more than 1/2 as long as spikelet, 3-veined, glabrous in sessile spikelet, appressed pubescent in pedicellate spikelet lower lemma strongly 9-veined, acuminate, glabrous in sessile spikelet and with spreading hairs in pedicellate spikelet; upper lemma lanceolate, acuminate, pale and slightly coriaceous; anther ca.1 mm long.

Perennial, stoloniferous. Culms branching and rooting at lower nodes, 50–100 cm tall. Leaf sheaths glabrous to papillose-pilose; leaf blades broadly linear, 5–15 × 0.3–0.6 cm, glabrous to papillose-pilose on both surfaces; ligule 1–2 mm. Inflorescence digitate; racemes 2–4, stiffly ascending to divaricate, 5–15(–20) cm, the longer sparsely spiculate at base; spikelets paired, not imbricate, appressed and appearing slightly sunken; rachis triquetrous, thick, scarcely winged. Spikelets lanceolate, 3.5–4.5(–6) mm, those of a pair different, lower spikelet glabrous, upper spikelet villous; lower glume very small, veinless; upper glume lanceolate, 1/2 as long as to equaling spikelet, 3–5-veined; lower lemma as long as spikelet, closely 7–11-veined, veins equidistant, thick, prominent, interspaces slitlike; upper spikelet with rows of silky hairs, usually also setose, the hairs spreading halo-like at maturity; upper lemma pallid, acuminate. Fl. and fr. Jun–Oct. 2n = 36, 72.

Tropical Asia. Taiwan, railroad-sides and littoral of the central and south parts.

Coastal sands. Fujian, Guangdong, Hainan, Taiwan [Indonesia, Malaysia, Palau Islands, Philippines, Thailand, Vietnam].

Paspalum heteranthum Hook. f., Fl. Brit. India 7(21): 16. 1896.

Paspalum heteranthum J. D. Hooker, Fl. Brit. India 7: 16. 1896 ["1897"], based on Panicum heteranthum Nees & Meyen (1841), not Link (1827); Digitaria baliensis Ohwi; D. banta-mensis Ohwi; D. dispar Henrard, nom. illeg. superfl; D. heter-antha var. hirtella L. C. Chia; D. shimadana Ohwi.