Vines woody. Branches shallowly 10-grooved, sparsely puberulous only on nodes. Leaves ternate; petiole 6.5--7.4 cm, sparsely puberulous; leaflet blades narrowly ovate to ovate, 6--9.5 × 2.7--4.5 cm, papery, both surfaces glabrous and reticulate, base subcordate to cordate-rounded, margin entire, apex acute to acuminate; basal veins prominent on both surfaces. Cymes axillary or terminal, many flowered, paniclelike; peduncle 3.5--7.5 cm, sparsely puberulous; bracts narrowly triangular to subulate, 3.5--5.5 mm. Flowers 1.6--3.7 cm in diam. Pedicel 1.5--2.5 cm, glabrous. Sepals 4, white, spreading, spatulate-linear to narrowly oblong, 0.8--2 cm × 2.2--6 mm, abaxially glabrous, adaxially glabrous, margin abaxially velutinous, apex acute. Stamens 6--7.5 mm, glabrous; anthers linear, 3.2--4.2 mm, apex obtuse. Ovaries pubescent. Style ca. 6 mm, densely villous. Fl. Apr.

* Evergreen broad-leaved forest margins in valleys; ca. 2100 m. SE Xizang, N Yunnan.