1. Mitracarpus hirtus (Linnaeus) Candolle, Prodr. 4: 572. 1830.
盖裂果 gai lie guo
Spermacoce hirta Linnaeus, Sp. Pl., ed. 2, 1: 148. 1762; Mitracarpus scaber Zuccarini; M. senegalensis Candolle; M. verticillatus (Schumacher & Thonning) Vatke; M. villosus (Swartz) Candolle; S. villosa Swartz; Staurospermum verticillatum Schumacher & Thonning.
Herbs, annual, branched, 40-80 cm tall; branches flattened to subterete or 4-angled, sometimes becoming woody in lower part, sparsely hirsute to villous. Leaves sessile; blade drying thinly papery, elliptic-oblong or lanceolate, 3-4.5 × 0.7-1.5 cm, adaxially scaberulous and usually also sparsely villosulous or pilosulous, abaxially moderately to densely villous or pilose, base acute to obtuse or rounded, apex acute; secondary veins 3-6 pairs; stipule sheaths 1-4 mm, villosulous or pilosulous to glabrescent, with 1-9 setae 1-5 mm. Inflorescences 5-20 mm in diam. (not including subtending leaves), villosulous or pilosulous; bracts linear, 1-2 mm. Calyx sparsely to densely puberulent or strigillose; ovary portion subglobose to ellipsoid, ca. 0.5 mm; limb deeply lobed; lobes unequal, triangular to lanceolate, 2 larger 1.8-2 mm, 2 smaller 0.8-1.2 mm, ciliate. Corolla funnelform, outside puberulent to glabrous; tube 1-1.5 mm, glabrous inside; lobes triangular to ovate, 0.5-1 mm, obtuse to acute. Capsules subglobose, ca. 1 mm in diam., scaberulous or sparsely puberulent; seeds dark brown, oblate-suboblong, ca. 0.8 mm. Fl. and fr. Apr-Nov.
Wastelands at highway sides; near sea level to 800 m. Hainan (Wanning), Hong Kong, Yunnan [native to the Antilles and Central, North, and South America; naturalized in tropical Africa, Asia, Australia, and Pacific islands].
The correct name for this species, whether Mitracarpus hirtus or M. villosus, has been controversial (for additional comments, see Taylor et al., Fl. Venez. Guayana 8: 497-847. 2004); most authors working with neotropical Rubiaceae today use the name M. hirtus. The capsules of all the Chinese specimens studied are smaller than those of neotropical plants. Fruit of similar size are found in plants of India (Sebastine & Ramamurthy, Bull. Bot. Surv. India 9: 291-292. 1967, see in particular f. 1-7) and may characterize several adventive populations. W. C. Ko (in FRPS 71(2): 212. 1999, as M. villosus) suggested that this species might be distylous, but Mitracarpus is monomorphic so far as known.