Description from
Flora of China
Herbs annual or perennial, glabrous. Stems 10-30 cm, usually branched, erect or ascending. Leaves opposite or 3- or 4-verticillate; pseudopetiole ca. 1.5 cm; leaf blade broadly ovate to suborbicular, 15-30 × 12-20 mm, apex rounded. Cymes terminal and subterminal, corymbiform, 5-10 cm in diam. Flowers unequally 5-merous; pedicel 3-5 mm. Sepals lanceolate-triangular, 1-1.2 mm, apex obtuse. Petals reddish purple, ovate-oblong, 3-4 mm, apex obtuse. Stamens 10, 3-5 mm. Nectar scales spatulate, minute, apex emarginate. Carpels suberect, oblong to lanceolate, 2-3 mm, glabrous. Styles ca. 1 mm. Follicles 3- or 4-seeded. Seeds brown, obovoid. Fl. Aug-Oct, fr. Oct.
Forested slopes; 800-2000 m. Henan, Hubei, Jiangsu, Shaanxi, Sichuan, Yunnan, Zhejiang [Bhutan, Myanmar, Nepal, Sikkim].