Vines woody. Branches subterete, not grooved, smooth, sparsely puberulous only at nodes, glabrous elsewhere; bud scales triangular, 4--5 × 3--3.5 mm, leathery, densely ciliolate. Leaves ternate; petiole 1--1.3 cm, sparsely pilose; terminal leaflet blade petiolulate, rhombic-ovate, 3-parted, ca. 1.4 × 1.2 cm, leathery, abaxially pilose on midvein, adaxially glabrous, base broadly cuneate; central lobe narrowly rhombic, 3-lobulate, lateral lobes obliquely narrowly oblong, 1-denticulate or entire, apex acuminate; lateral leaflet blades subsessile, obliquely narrowly ovate, ca. 1.2 × 0.8 cm, 2- or 3-lobulate; basal veins nearly flat. Flowers 2 or 3, borne with 2 or 4 leaves on axillary buds of old branches, 2.7--3.2 cm in diam.; pedicel 2--3 cm, puberulous. Sepals 4, spreading, purple-red, obovate or narrowly so, rarely elliptic, 1.3--1.7 × 0.8--1.35 cm, abaxially sparsely puberulous, adaxially glabrous, apex rounded, mucronulate. Stamens 6--11 mm, glabrous; anthers linear, 2--2.8 mm, apex obtuse. Ovaries glabrous; style ca. 7 mm, densely villous. Fl. Jun.

* E Xizang (Ningjing Shan).