Its leaves are opposite, oblong-ovate, 4-6 cm long, and sparsely silvery hairy, particularly along the veins.

The leaf margins feature a pair of large teeth in the lower third, occasionally becoming coarsely toothed towards the apex.

The petiole is very short, measuring 0-2 mm long, and while not winged, the leaf base is somewhat decurrent.

[4] Thunbergia annua can be found within many countries across Africa such as: Botswana, Ethiopia, Kenya, Niger, Sudan, Tanzania, Uganda and Zimbabwe.

[2][4] The species inhabits seasonally dry grassland habitats where it can be found growing within clay soils.