Description from Flora of China
Herbs perennial, 30--100 cm tall. Stems arcuately elongate from erect base, quadrangular, ± winged on ridges. Leaves opposite; petiole 0.7--2.5 cm, narrowly winged; leaf blade ovate to ovate-lanceolate, 4.5--8 X 2.5--5.5 cm, glabrescent or adaxially ± strigillose, minutely brown glandular, base cordate, margin obscurely undulate and densely papillate, apex acute; veins 4--6 pairs; veinlets obscure. Inflorescences in axils of leaves. Pedicel arcuate-spreading, 1--2.5 cm, thickened toward apex. Flowers usually paired. Calyx lobes ovate-lanceolate, ca. 6.5 mm, glandular on margin, costate. Corolla cream-yellow, ca. 7 mm, deeply parted; lobes broadly ovate, ca. 6 X 4 mm. Filaments connate basally into a ca. 1.3 mm high ring, free parts ca. 0.8 mm; anthers ca. 2 mm, basifixed, opening by short slits. Capsule subglobose, 4--4.5 mm in diam., ca. as long as to shorter than calyx. Fl. Mar.
* Mixed woodlands, gullies; 1900--2200 m. W Guizhou, S Yunnan.