Description from Flora of China
Roots fusiform, carrot-shaped or cylindrical, 12-50 × 1.5-8 cm. Stems twining, 2-4 m, branched, sparsely white hirsute. Leaves on main stem and branches alternate, those on branchlets subopposite; petiole 0.5-2 cm, sparsely white hirsute; blade abaxially gray-green, adaxially green, ovate, 0.5-3 × 0.5-2.5 cm, abaxially hirsute, adaxially hispidulous, base subcordate, truncate, or rounded, margin shallowly sinuate or crenulate, apex obtuse or acute. Flowers solitary, terminal on branchlets or opposite to leaves; pedicels 2.5-6 cm, hirsute. Calyx tube fully adnate to ovary, semiglobose, with 10 conspicuous sparsely white hirsute ribs; lobes rhombic, elliptic, or ovate, 9-13 × 4.5-8 mm, conspicuously veined, abaxially white hirsute, margins serrate, separated by broad flat sinuses. Corolla pale yellow-green with dark red-purple on lobes and sometimes at base, globose-campanulate, 2-2.5 × 2.5-3.7 cm; lobes broadly triangular, ca. 1/2 as long to nearly as long as tube. Filaments slightly dilated; anthers ellipsoid, 4-6 mm. Capsule semiglobose below, conical and rostrate above, 14-15 × 15-18 mm. Seeds numerous, yellow-brown, ellipsoid or ovoid, wingless, smooth. Fl. and fr. Jul-Oct.
● Stony mountain meadows, wooded limestone cliffs, scrub by streams; 2500-3700 m. W Sichuan, E Xizang, NW Yunnan (Dêqên, Lijiang).