Herbs perennial. Stems prostrate to decumbent, 7--15(--30) cm, usually branched from base, with grayish multicellular hairs. Leaves opposite; petiole 2--5(--10) mm, narrowly winged; leaf blade broadly ovate to suborbicular, 1--2.5 X 0.7--2 cm, pubescent, transparent glandular punctate, base rounded to subtruncate, apex acute to obtuse; veins 2 or 3 pairs; veinlets inconspicuous. Pedicel recurved in fruit, 3--8 mm. Flowers solitary, axillary. Calyx lobes lanceolate, 3--4 mm, enlarging to 7--8 mm in fruit, pubescent. Corolla yellow, deeply parted, ca. as long as calyx, 5--8 mm in diam.; lobes triangular-ovate, transparent glandular punctate. Filaments connate basally into a ca. 1 mm high ring, free parts 1--2 mm; anthers ovate, dorsifixed, opening by lateral slits, ca. 1 mm. Ovary pubescent; style 2--3 mm. Capsule subglobose, 3--4 mm in diam., pubescent at apex. Fl. Mar-Apr. 2n = 18, 20, 22.

Grassy banks, ditches, streamsides; 500--800 m. Hainan, Jiangsu, Taiwan, Zhejiang [Bhutan, India (Darjeeling), Indonesia, Japan, Kashmir, Korea].