Vines woody. Branches terete, subglabrous. Leaves simple; petiole 0.8--3.5 cm; leaf blade elliptic, oblong, or narrowly ovate, 5.5--16 × 2--8.4 cm, papery to subleathery, both surfaces glabrous, base broadly cuneate to cuneate, margin entire or rarely minutely denticulate, apex acuminate; basal veins abaxially ± prominent. Cymes axillary, 1-flowered; peduncle 0.4--3.5 cm; bracts narrowly triangular, ca. 3.5 mm. Flowers ca. 2 cm in diam. Pedicel 3.5--8 cm, glabrous. Sepals 4, greenish yellow, erect, oblong to ovate-oblong, 1.8--3.1 × 0.6--1 cm, abaxially glabrous except for velutinous margin, adaxially densely puberulous or glabrous, apex ± acute. Stamens 1.5--2.3 cm; filaments densely pubescent; anthers oblong to narrowly oblong, 3--5 mm, abaxially densely pubescent, apex obtuse or minutely apiculate. Ovaries pubescent. Style 8--11 mm, densely villous. Fl. Sep, fr. Oct.

* Forests; 800--2100 m. W Guizhou, W Hubei, S Sichuan, NE Yunnan.