Japanese Paspalum

This species is similar to Paspalum scrobiculatum, but most easily distinguished by its pale fertile floret. The marginal pubescence on the spikelets is a good confirmatory character.

Perennials; culm tufted, 40-90 cm tall, nodes pilose. Blade linear, pilose, 10-30 cm long, 5-8 mm wide; sheath long, pilose; ligule membranaceous, truncate, 1-2 mm long. Inflorescence of racemose racemes, 5-20 cm long; racecmes 3-5, ridged on main axis, 5-10 cm long, axils of racemes with tuft of hairs; rachis ca. 0.8 mm wide; pedicel short. Spikelets 2.5-2.7 mm long, broadly elliptic or elliptic, rounded or slightly mucronate, sparsely covered with spreading hairs on margins; upper glume and lower lemma similar, 3-veined, membranaceous; upper lemma coriaceous, as long as spikelet, slightly shiny.

Perennial from short knotty rootstock. Culms tufted, erect, 50–100 cm tall, nodes glabrous or pilose. Leaf sheaths keeled, hirsute; leaf blades linear, 10–25 × 0.5–0.8 cm, hirsute on both surfaces, rarely glabrous, apex acuminate; ligule 0.5–1.5 mm. Inflorescence axis 1–9 cm; racemes 2–6, 3–10 cm, laxly ascending or spreading, axils pilose; spikelets commonly paired at least in central part of raceme or a vestigial 2nd spikelet present; rachis ca. 1 mm wide, margins scaberulous; pedicels minutely puberulous. Spikelets elliptic to orbicular-elliptic, plumply plano-convex, 2.5–3 mm, rounded or subacute; upper glume membranous, 3-veined with laterals marginal, sparsely pubescent especially along margins; lower lemma similar but glabrous; upper lemma pallid, as long as spikelet, coriaceous, punctulate-striate, obtuse. Fl. and fr. May–Oct. 2n = 20, 40.

China and Japan. Taiwan, in mountainous areas of the northern part.

Fields, waste places, usually on moist soils. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Shandong, Sichuan, Taiwan, Yunnan, Zhejiang [Bhutan, India (Darjeeling, Sikkim), Japan, Korea].

Paspalum dissectum Thunberg, Fl. Jap. 45. 1784, not (Linnaeus) Linnaeus (1762); P. scrobiculatum Linnaeus var. thunbergii (Kunth ex Steudel) Makino.