Shrubs climbing. Stems terete, shallowly striate, densely dusty yellow to brownish hirsute. Petiole 6-15 cm, densely hirsute; leaf blade cordate to orbicular, 11-13 × 9-32 cm, papery, both surfaces moderately to densely hirsute, veins palmate, 2 pairs from base, base cordate or auriculate, sinus 3-5 cm deep, apex obtuse or acute. Racemes in axils of leafy shoots, 2- or 3-flowered. Pedicel pendulous, 2.5-3.5 cm, hirsute; bractlets subulate, 3-6 mm. Calyx limb dark purple, throat yellow, 4-5 cm; tube horseshoe-shaped, abaxially densely hirsute; basal portion of tube 20-35 × 3-10 mm; limb discoid-suborbicular, 3.5-4.5 cm in diam., distinctly 3-lobed; lobes broadly deltoid. Anthers oblong, ca. 2 mm. Gynostemium 3-lobed. Capsule cylindric, 8-10 × 2 cm, dehiscing basipetally. Seeds ovoid, 5 × 4 mm. Fl. Mar-May, fr. Aug-Sep.