海南马唐 hai nan ma tang

Digitaria hainanensis Hitchcock ex Keng; Digitaria micro-bachne (J. Presl) Henrard; D. microstachya Henrard; D. pruriens (Fischer ex Trinius) Buse; D. sanguinalis (Linnaeus) Scopoli var. pruriens (Fischer ex Trinius) Prain; Panicum microbachne J. Presl; P. pruriens Fischer ex Trinius; P. san-guinale Linnaeus var. microbachne (J. Presl) Hackel; Syn-therisma microbachne (J. Presl) Hitchcock.

Annual. Culms tufted, decumbent, branching and rooting at lower nodes, 30–100 cm tall. Leaf sheaths glabrous or papillose-pilose; leaf blades linear-lanceolate, 5–20 × 0.3–1 cm, glabrous on both surfaces, papillose-pilose at base, base subrounded, apex acuminate; ligule 1–2 mm. Inflorescence digitate or subdigitate, axis 1–4 cm; racemes 5–12, stiff, 5–15 cm; spikelets paired, imbricate by about 2/3 their length; rachis triquetrous, narrowly winged, ca. 0.6 mm broad, margins scabrous. Spikelets narrowly lanceolate-oblong, 2–2.5(–3) mm, acute; lower glume absent or a minute rim; upper glume up to 1/3 as long as spikelet, 1–3-veined, margins ciliate, apex villous with overtopping hairs; lower lemma as long as spikelet, 5–7-veined, veins evenly spaced or with a wider interspace flanking the midvein, lateral intervein spaces and margins appressed pubescent to villous, rarely ciliate or setose; upper lemma yellowish to gray, subequaling lower lemma, acuminate. Fl. and fr. Jun–Nov. 2n = 27, 36, 54, 72.

Moist slopes, stream banks, roadsides and weedy places. Fujian, Guangdong, Guangxi, Guizhou, Hainan, Taiwan, Yunnan [Bangladesh, Bhutan, India, Indonesia, Japan, Malaysia, Myanmar, Nepal, Thailand, Vietnam; E Africa (Tanzania), Australia, Indian Ocean Islands (Seychelles), Madagascar, Pacific Islands].

This coarse, weedy species is widespread in warm parts of Asia. Spikelet pubescence is very variable, as in most members of the complex around Digitaria ciliaris, but the species can be readily distinguished by the lack of a lower glume and the presence of only a very short upper glume.

Specimens have sometimes been misidentified as Digitaria corymbosa Merrill. True D. corymbosa is a synonym of D. compacta (Roemer & Schultes) Veldkamp from India.