三脉耳草 san mai er cao

Oldenlandia trinervia Retzius, Observ. Bot. 4: 23. 1786; Hedyotis rotundifolia Sprengel, nom. illeg. superfl.

Herbs, annual, prostrate to weakly erect, to 15 cm tall; stems 4-angled to 4-winged, hirsute to pilose. Leaves subsessile to petiolate; petiole to 2 mm, pilose to hirsute; blade drying papery, ovate, elliptic, or suborbicular, 0.3-1.2 × 0.6-1 cm, adaxially glabrous, abaxially glabrous or sparsely strigillose to hispid, base obtuse and shortly decurrent, margins usually ciliate, apex obtuse and shortly acuminate; secondary veins 2 or 3 pairs; stipules fused to petiole bases, hispidulous to villosulous, truncate, ca. 0.5 mm, irregularly erose and with 1-3 narrowly triangular to linear lobes or bristles 0.3-1 mm. Inflorescences axillary, 1-flowered to 2-4-flowered and cymose or fascicled, pilose, subsessile; pedicels to 1.5 mm. Flowers subsessile to pedicellate. Calyx pilosulous to hispidulous; hypanthium portion subglobose, ca. 1 mm; limb lobed nearly to base; lobes triangular, 1-1.2 mm. Corolla white, rotate, apparently glabrous; tube ca. 0.5 mm; lobes 1-2 mm. Anthers exserted or included, 0.5-1 mm. Stigmas included. Fruit capsular, subglobose, somewhat didymous, 1-2 × 1-1.5 mm, pilosulous or hispidulous, loculicidally dehiscent across top; seeds several, black, angled. Fl. and fr. Oct-Mar.

Sparse forests on mountains. Hainan (Ledong) [India, Indonesia, Malaysia, Sri Lanka, N Vietnam].

The descriptions seen suggest that this is a rather distinctive species. The description here is compiled from Dutta and Deb (Taxon. Rev. Hedyotis. 2004) and Augustine (J. Econ. Taxon. Bot. 26: 91. 2002).

The synonym Hedyotis rotundifolia was attributed by W. C. Ko (in FRPS 71(1): 76. 1999) to Candolle, but Candolle clearly indicated (Prodr. 4: 420. 1830) that Sprengel was the author of the name. W. C. Ko gave the range of this species as including "Tropical Africa," but Verdcourt (Fl. Trop. E. Africa, Rub. (Pt. 1), 279-280. 1976) noted that throughout Africa this name was long incorrectly applied to Oldenlandia goreensis (Candolle) Summerhayes (= H. goreensis Candolle); thus, H. trinervia is not currently known from Africa.