Key for Thunbergia Retz.

1Petiole conspicuously alate; corolla orange (or yellow sometimes white) with a dark purple, glandular spot in throat
1'Petiole naked; corollas not colored as above, lacking glandular spot in throat
2Erect to arching shrub; leaves, 2-5.5 cm long, acute to attenuate at base
2'Woody or herbaceous vines; leaves more than 5.5 cm long or, if less, then truncate to subcordate at base
3Calyx with 12-17 subulate lobes; corolla white, 30-40(-50) mm long, externally pubescent
3'Calyx annular, unlobed; corolla light purple, lavender or white with a yellowish throat, 60-80 mm long, externally glabrous