2. Richardia scabra Linnaeus, Sp. Pl. 1: 330. 1753.
墨苜蓿 mo mu xu
Richardia pilosa Ruiz & Pavon; Richardsonia scabra (Linnaeus) A. Saint-Hilaire.
Herbs, annual, decumbent or suberect, to 80 cm or longer; stems flattened to subterete, hirsute. Petiole 5-10 mm, hirsute to glabrescent; leaf blade drying membranous to thickly papery, ovate, elliptic, or lanceolate, 1-5 × 0.5-3.5 cm, both surfaces scabrous to glabrescent, base acute to cuneate, apex acute to obtuse; stipule sheaths 1-4 mm, pilose to pilosulous, with 3-15 setae 2-5 mm. Inflorescences ca. 1 cm in diam. (not including leaflike bracts or subtending leaves). Calyx with ovary portion obovoid, 1-1.5 mm, papillose to hispidulous; lobes 6, lanceolate or narrowly lanceolate, 1.5-3.5 mm, glabrescent, margins ciliate, apex acute. Corolla white, glabrous inside and outside; tube 2-8 mm; lobes 6, triangular, 1-3 mm. Fruit with mericarps 3, ellipsoid to obovoid, in cross-section triangular to somewhat rounded, 2-3.5 mm, dorsally densely papillose to hispidulous, ventrally with 1 narrow groove along length of face. Fl. and fr. Feb-Nov.
Wastelands; sea level to 200 m. Naturalized in Guangdong, Hainan, and Taiwan [native to the Antilles and North and South America; adventive and naturalized occasionally throughout Old World tropics].
H. S. Lo (in FRPS 71(2): 203. 1999) noted that this species was introduced to China in the 1980s.