Common Names: Bengal clock vine, clock vine, sky flower.
Thunbergia is a genus of flowering plants in the Family Acanthaceae, native to tropical regions of Africa, Madagascar and southern Asia.
Thunbergia was named for Carl Peter Thunberg.
Some are frequent garden escapes, becoming invasive species; they are regarded as environmental threats in Australia. (Wikipedia.)
Tis specimen was cut from a fence in my backyard.