Thunbergia genus is is belong to Acanthaceae family, consist of about 90 old world species. Thunbergia, named in 1780 by Retzius, honours of Carl Peter Thunberg (1743-1828), a Swedish botanist, doctor, explorer and author who was one of the pupil of Linnaeus.

Thunbergia alata naturaly found in Eastern Tropical Africa, southwards through the eastern parts of South Africa. The species name is from the Latin alatus, meaning winged. It refers to the winged petioles but it could also allude to the seeds that have projections looking rather like wings. It has become naturalized in Asia and Malesia and is consedered invasive in Hawaii and Australia.

Black-Eyed Susan is well known as a fast-growing, long-flowering, creeper. It is a perennial climber about up to 400cm high or wide with many twining stems. The leaves are heart or arrow shaped, softly hairy and sometimes toothed. Many flowers are borne singly in leaf axils. The flowers look daisy like at a distance, but they are actually tubular. Five over lapping petals surround a brownish-purple center tube. The corolla is obliquely trumpet-shaped and is usually bright orange in wild plants. The inside of the tube is a striking dark maroon or purplish black. New cultivars are being created with white, cream, peach coloured, yellow, deep orange or nearly red flowers. The fruit is like a bird’s head with a spherical base and a long ‘beak’.

Thunbergia alata needs full sun or light shade. It is half-hardy, needing fairly warm conditions but, with protection, young plants can survive some frost. In cold areas it is used as an annual. Flowers all summer but can continue all year in warmer areas. Propagation is made by seeds. Seeds germinates easily in a damp mixture of fine humus-rich soil with some sand. The flowers reflect ultra violet light in a pattern that is visible to insects but not to humans. This helps insects find the centre of the flower.

In East Africa, Black-Eyed Susan is used as a vegetable or stock feed. Medicinally it is used for skin problems, cellulitis, back and joint pains, eye inflammation and piles. Some people can get contact dermatitis from it.

In warmer parts of the world, Thunbergia alata is a general favourite as it is not fussy about soil, needs only moderate water, is mostly evergreen and covers ugly places beautifully. Black-Eyed Susan grows quickly and starts flowering at an early age. It can be trimmed if it gets too big. Light trimming in spring will encourage flowering. If frost is a problem, plant can be cut right back and it will probably resprout.

Use in Landscape: Used mainly as an ornamental plant, makes a good screen when used to cover unsightly dead trees or walls. It needs some support, as it cannot cling. Use fences, trellises, arches, arbours and pillars or a lightly shading tree. Alternatively, this creeper may be planted in groups as a ground cover, or on a bank or terraces where it can trail downwards. Also used in hanging baskets.

Blue and orange look well together so Black-Eyed Susan can be planted near Felicia amelloides or blue Agapanthus africanus. This creeper would go well behind white Agapanthus africanus, Dietes grandiflora and Carissa macrocarpa (Natal plum).