Thunbergia gregorii, commonly known as orange clockvine or orange trumpet vine, is a herbaceous perennial climbing plant species in the family Acanthaceae, native to East Africa and sometimes cultivated as an ornamental vine. The bright, pure all-orange flowers distinguish it from the related black-eyed Susan vine (Thunbergia alata).[1]
Spencer Le Marchant Moore described the species in 1894, naming it after John Walter Gregory.[1] Within the genus Thunbergia, it is most closely related to T. alata, the two being placed in the subgenus Parahexacentris.[2] The common name of clockvine relates to the vine spiralling upwards in a clockwise direction.[1]
Thunbergia gregorii is an evergreen vine that grows to 8–10 ft. tall, or if left without support can become an extensive groundcover. It looks like the related black-eyed Susan vine (T. alata), but without the black eye.
Thunbergia gregorii is native to east Africa, and is pollinated by bees.[2]
Hardy to -1 C, Thunbergia gregorii flowers more profusely and even year-round in warmer climates, while restricted to summer and autumn in cooler climates.[3] It has received the Royal Horticultural Society's Award of Garden Merit.[4]
Propagation is by cuttings taken in the summer.[1]