Description from Flora of China
Marsdenia globifera Tsiang; M. tinctoria var. brevis Costantin; M. tinctoria var. tomentosa Masumune ex Tsiang & P. T. Li.
Lianas to 5 m, densely to sparsely pubescent when young, glabrescent. Petiole 1-4 cm; leaf blade oblong to broadly ovate, 5-13 × 2-7 cm, thin papery, bluish when dry, base rounded to cordate, apex acuminate; lateral veins 5-7 (-10) pairs. Inflorescences dense, globose to long racemelike clusters of cymules, (1.5-)3-15 cm; peduncle (0.5-)2.5-5 cm. Pedicel 3-5 mm. Sepals suborbicular, ca. 2 mm. Corolla yellowish white, dark blue when dry, urceolate, 3.5-4(-6) mm long, throat with a ring of hairs, otherwise glabrous; tube ca. 2.5 mm; lobes ovate, 1-1.5 mm, apex rounded. Corona lobes 5, lanceolate, as long as anthers. Pollinia narrowly oblong. Stigma head discoid, slightly convex at apex. Follicles oblong-lanceolate, 5-10 cm × 8-10 mm, pilose to subtomentose. Seeds ovate, ca. 10 × 3 mm; coma 1-2 cm. Fl. Mar-Nov, fr. Jul-Dec.
The bark, leaves, and flowers are used in making a blue dye.
As here delimited, Marsdenia tinctoria includes a wide range of forms which need more detailed investigation, and several taxa might be involved. There is also considerable variation in
the relative length of corona to anthers and in the size, shape, and indumentum of fruits. The Chinese material has distinctly narrower and often paler leaves than Indian material and also
lacks the very long spiral rachis of typical M. tinctoria. Marsdenia globifera was based on material with diseased flowers.
Humid mixed woods; 400-1000 m. Guangdong, Guangxi, Guizhou, Hainan, Hubei, Hunan, Sichuan, Taiwan, Xizang, Yunnan [Bhutan, India, Indonesia, Japan (Ryukyu Islands), Laos, Malaysia, Myanmar, Nepal, Philippines, Sri Lanka, Thailand, Vietnam]