Thunbergia grandiflora is an evergreen vine in the family Acanthaceae. It is native to China, India, Nepal, Bangladesh, Indochina and Myanmar and widely naturalised elsewhere. Common names include Bengal clockvine, Bengal trumpet, blue skyflower, blue thunbergia, blue trumpetvine, clockvine, skyflower and skyvine.
Plants may grow to about 20 metres in height and have a long root system with a deep tap root. The stalked, opposite leaves, which have a rough surface, are quite variable in shape. They may be triangular or ovate and the margins may be toothed, lobed or entire. Length is up to 200 mm and width is up to 60 mm, which are typically smaller than the very similar T. laurifolia.
The blue to mauve flowers are about 8 cm across with a 4 cm long tube that is pale yellow inside. These are followed by pods containing seeds that are ejected several metres upon ripening. Plants also reproduce from segments that are washed down watercourses.
