Vines woody. Branches shallowly 8-grooved, glabrous or sparsely puberulous. Leaves all ternate or distal ones simple; petiole 5--7 cm, base sparsely puberulous; leaflet blades ovate to narrowly ovate, 5.5--13 × 2.2--6.5 cm, papery, abaxially glabrous, adaxially sparsely puberulous near base, both surfaces reticulate, base rounded, margin entire, apex acuminate; basal veins abaxially prominent. Cymes axillary, often paniclelike, 1- to many flowered, glabrous; peduncle 4--5.5 cm; bracts linear, 4--7 mm. Flowers ca. 1 cm in diam. Pedicel 1.5--3.2 cm, glabrous or puberulous. Sepals 4, white, erect, oblong-lanceolate, ca. 15 × 4--5 mm, abaxially puberulous or densely so, or glabrous except for velutinous margin, adaxially puberulous only near obtuse and recurved apex. Stamens ca. 1.4 cm; filaments densely villous; anthers narrowly oblong, 2.5--3 mm, glabrous, apex obtuse. Ovaries pubescent. Style ca. 1 cm, densely villous. Fl. Oct--Dec, fr. Mar.

Forests, along streams; 1000--2400 m. SE Xizang, C and W Yunnan [Bhutan, NE India, N Myanmar, E Nepal, Sikkim, N Thailand].