Thunbergia erecta has attractive, small, dark green leaves and tubular flowers which in the most common form are rich purple with a yellow throat; there is also a white-flowering form, which seems to have smaller leaves and is somewhat less robust. It responds well to regular pruning and can be shaped into a very bushy shrub, though this inhibits blooming. It prefers full sun and well-drained soil but will bloom in partial shade. These lovely, slightly fragrant blooms occur all year long, especially in the summer.
Background: Thunbergia erecta belongs to family Acanthaceae.
King’s Mantle, Buch Clock Vine
Source: http://www.toptropicals.com/, hort.ifas.ufl.edu
Photograph taken at Fort Canning Park, Singapore by Cher