10. Digitaria ciliaris (Retzius) Koeler, Descr. Gram. 27. 1802.
纤毛马唐 xian mao ma tang
Annual. Culms decumbent at base, branching and rooting at lower nodes, 30–100 cm tall. Leaf sheaths ± pilose; leaf blades linear to linear-lanceolate, 5–20 × 0.3–1 cm, adaxial surface usually pilose, margins thickened and scabrous; ligule 1–2 mm. Inflorescence digitate or subdigitate, axis short; racemes 3–10, 5–17 cm; spikelets paired, imbricate by about 2/3 their length; rachis winged, ca. 1 mm broad, midrib triquetrous, margins scabrous. Spikelets lanceolate, 2.5–3.5 mm, acute; lower glume very small, triangular; upper glume lanceolate, 2/3–4/5 as long as spikelet, 3-veined, pilose; lower lemma as long as spikelet, 7-veined, veins evenly spaced or a broader glabrous interspace flanking the midvein, lateral interveins appressed pubescent to ciliate or villous, sometimes with a halo-like fringe, sometimes setose; upper lemma yellowish green, gray or pale brown, elliptic, as long as lower lemma, apex acuminate. Fl. and fr. May–Oct. 2n = 36, 54, 72.
Roadsides, weedy places. Anhui, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Jilin, Liaoning, Nei Mongol, Ningxia, Shaanxi, Shandong, Shanxi, Sichuan, Taiwan, Xinjiang, Xizang, Yunnan, Zhejiang [throughout the tropics and subtropics, but rare in Africa].
Digitaria ciliaris is a pantropical, weedy annual very variable in spikelet pubescence and nervation. It lies at the center of a complex of similar and somewhat intergrading, weedy species including D. bi-cornis, D. cruciata, D. henryi, D. radicosa, D. sanguinalis, and D. seti-gera. Occasionally intermediate specimens will be encountered that are difficult to place.
Most species in this complex include forms with or without stiff, glassy bristles near the margins of the lower lemma. These lie flat along the lemma when young, coloring yellow and spreading as a conspicuous pectinate fringe at maturity. The pectinate form of Digitaria ciliaris is sometimes distinguished at varietal rank.