21. Digitaria violascens Link, Hort. Berol. 1: 229. 1827.
紫马唐 zi ma tang
Digitaria chinensis (Nees) A. Camus (1923), not Hornemann (1819); D. pertenuis Buse; D. thwaitesii (Hackel) Henrard var. tonkinensis Henrard; D. violascens (Link) var. villosa Keng; Panicum steudelianum Domin; P. violascens (Link) Kunth; Paspalum chinense Nees; P. minutiflorum Steudel (1853), not Desvaux (1831); Syntherisma chinensis (Nees) Hitchcock.
Annual. Culms loosely tufted, infrequently shortly stoloniferous, 20–60 cm tall. Leaf sheaths glabrous or pilose, especially at mouth; leaf blades linear-lanceolate, 5–15 × 0.2–0.6 cm, scabrous, glabrous or adaxial surface pilose at base, apex acute; ligule 1–2 mm. Inflorescence subdigitate; racemes (2–)3–7(–10), ascending, 3–12 cm; spikelets ternate; rachis ribbonlike, winged, 0.5–0.8 mm broad, midrib low and rounded, margins serrate; pedicels angular, scabrous, with discoid tips. Spikelets elliptic-oblong, 1.4–1.9(–2.5) mm, hairs verrucose, sometimes hook-tipped; lower glume absent; upper glume lanceolate, slightly shorter than spikelet, 3(–5)-veined, intervein spaces and margins appressed-pubescent; lower lemma as long as spikelet, 5–7-veined, intervein spaces and margins pubescent, but usually glabrous flanking the middle vein; upper lemma dark brown or purplish black at maturity. Anthers 0.3–0.6 mm. Fl. and fr. Jul–Nov. 2n = 36.
Hillsides, roadsides, weedy places; ca. 1000 m. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Qinghai, Shandong, Shanxi, Sichuan, Taiwan, Xinjiang, Xizang, Yunnan, Zhejiang [Bhutan, India, Indonesia, Malaysia, Myanmar, Nepal, Pakistan, Philippines, Sri Lanka, Thailand, Vietnam; Australia, South America].
This widespread, weedy species is closely related to Digitaria longiflora, and there is some overlap between the two. Digitaria violas-cens tends to be tufted rather than stoloniferous, with 3 or more longer racemes, angular, scabrous pedicels, a shorter, 3-veined upper glume, and distinctive, blackish fruits.