Description from Flora of China
Herbs or suffrutescent subshrub, erect, to 1 m tall. Branches ribbed to narrowly winged, puberulent at nodes. Leaves petiolate; leaf blade rhomboid-ovate to rhomboid-lanceolate, to 3.6 X 1.5 cm, glabrous, glandular punctate, base cuneate, margin toothed above middle, sometimes slightly double serrate, or subentire, apex obtuse. Flowers usually axillary, (1 or)2 per node. Pedicel 5-10 mm, glabrous. Bracteoles absent. Calyx lobed to base; lobes 4, ovate-oblong, ca. 2 mm, margin ciliate, apex obtuse. Corolla white, ca. 4 mm. in diam.; tube densely hairy at throat; lobes 2-3 mm, margin erose-denticulate, apex obtuse; upper lobe slightly larger than others. Stamens exserted. Style erect; stigma truncate to 2-parted. Capsule 2-3 cm in diam., columella persistent.
Waste places, beside trails, occasionally on mountain slopes; below 1400 m. Fujian, Guangdong, Guangxi, Taiwan, Yunnan [throughout tropics and subtropics].