Description from Flora of China
Trees, to 20 m tall; crown broad, umbelliform. Bark brown-gray. Twigs conspicuously lenticellate, viscid glandular when young. Leaf blade cordate, ca. 40 cm, abaxially densely to sparsely hairy, adaxially sparsely hairy, apex acute. Thyrses pyramidal to narrowly conical, to 50 cm; cymes 3- or 4-flowered; peduncle 1-2 cm, nearly as long as pedicels. Calyx shallowly campanulate, ca. 1.5 cm, outside tomentose; lobes to 1/2 or more calyx length, ovate-oblong. Corolla purple, funnelform-campanulate, 5-7.5 cm, ridged ventrally, outside glandular, inside glabrous; limb ca. 4.5 cm in diam. Stamens to 2.5 cm. Ovary ovoid, glandular. Style shorter than stamens. Capsule ovoid, 3-4.5 cm, densely viscid-glandular hairy; pericarp ca. 1 mm; persistent calyx lobes flat. Seeds 2.5-4 mm including wing. Fl. Apr-May, fr. Aug-Sep.
* Cultivated or wild; below 1800 m. Anhui, Gansu, Hebei, Henan, Hubei, Hunan, Jiangsu, Jiangxi, S Liaoning, Shaanxi, Shandong, Shanxi, N Sichuan [cultivated in North America, Europe, Japan, and Korea].