脉耳草 mai er cao

Hedyotis capituliflora Miquel; H. costata (Roxburgh) Kurz (1876), not R. Brown ex G. Don (1834); Metabolos lineatus Bartling ex Candolle; Spermacoce costata Roxburgh.

Herbs, annual or perennial, diffusely branched, weak to clambering or prostrate, to 60 cm tall; stems flattened, 4-angled, or subterete, sometimes sulcate, densely villous or hirsute with trichomes drying golden yellow. Leaves subsessile to petiolate; petiole 1-10 mm, densely hirtellous to villous; blade drying membranous to papery, lanceolate, elliptic-lanceolate, or elliptic, 2-8 × 0.5-3 cm, adaxially sparsely to densely strigose and/or strigillose to hirsute on lamina and moderately to densely pilosulous on principal veins, abaxially sparsely strigillose to glabrescent on lamina and densely strigose to hirsute on principal veins, base cuneate to obtuse and frequently decurrent, apex acute to usually acuminate; secondary veins 4-6 pairs; stipules fused to petiole bases, truncate to triangular, 2-4 mm, moderately to densely hirtellous, hirsute, or villous, with 3-5 linear or setose lobes 2-5 mm. Inflorescences axillary, congested-cymose, capitate, or fasciculate, 5-20 mm, densely hirtellous to hirsute, several to many flowered, pedunculate; peduncles 1-3 per leaf axil, 2-12 mm; bracts subulate, to 1 mm. Flowers sessile or subsessile, distylous. Calyx densely hirtellous to villosulous; hypanthium portion turbinate to obconic, ca. 0.5 mm; limb lobed nearly to base; lobes lanceolate to triangular, 0.3-1 mm. Corolla white or purple, tubular to funnelform, outside puberulent to pilosulous; tube 1.2-1.5 mm, pubescent in throat; lobes narrowly elliptic to triangular, 0.8-1.2 mm. Anthers 0.5-1 mm, exserted. Stigma 0.3-0.6 mm, exserted. Fruit indehiscent, subglobose, 0.8-1.5 mm in diam., pilosulous; seeds 6-8, black, trigonous. Fl. and fr. Jul-Nov.

Forest margins in valleys, open fields, grassy slopes; 400-2000 m. Guangdong, Guangxi, Hainan, Yunnan [India, Indochina, Indonesia, Malaysia, Philippines, Thailand].

This species has been treated by many previous authors under the name Hedyotis costata; the basionym of that name, Spermacoce costata Roxburgh, is indeed the oldest name for this species, but that epithet was previously occupied for another species in Hedyotis when Kurz published his name and, thus, was blocked from transfer.