Description from Flora of China
Aristolochia yunnanensis Franchet; A. yunnanensis var. meionantha Handel-Mazzetti; Isotrema griffithii (J. D. Hooker & Thomson ex Duchartre) C. E. C. Fischer.
Shrubs climbing. Stems terete, striate, densely reddish brown villous. Petiole 5-10 cm, densely villous; leaf blade cordate to orbicular, 10-28 × 8-26 cm, papery, abaxially densely red-brown or white villous, adaxially sparsely pubescent, veins palmate, 3-4 pairs from base, base cordate to auriculate, sinus 3-6 cm, apex acute or shortly acuminate. Flowers solitary. Peduncle pendulous, ca. 10 cm, villous; bractlets ovate, 3 × 2.5 cm, inserted below middle of peduncle. Calyx dark purple with yellow spots on tube and limb, throat blood red, 10-12 cm; tube horseshoe-shaped, abaxially villous; basal portion of tube ca. 80 × 35 mm; limb discoid-rotund, 6-12 cm in diam., shallowly 3-lobed; lobes broadly deltoid. Anthers oblong, 3-4 mm. Gynostemium 3-lobed. Capsule cylindric, 10-18 × 2.5-3 cm, dehiscing basipetally. Seeds ovoid, ca. 4 × 3 mm, upper surface plano-convex, lower surface deeply concave, with a septumlike funiculus at center, rugose or smooth. Fl. Apr-Jul, fr. Aug-Oct.
Mixed forests; 2100-2800 m. Xizang, Yunnan [Bhutan, NE India, Myanmar, Nepal, Sikkim].