Thunbergia are tropical and subtropical climbers native to Africa and South Asia. There are over 100 varieties of Thunbergia, a majority of these being perennial vines but there are also bush form and annuals which are grown from seed. The annual Thunbergia is commonly known as ‘black eyed Susie’.
More recently there have been many new cultivars of Thunbergia alata introduced, with their bright and very free flowering displays making them a popular choice for the garden. Although perennial, it is best to overwinter these plants in a frost free environment. If left outside they need to be very sheltered.
Good examples of these are Thunbergia ‘Orange and Red’ and Thunbergia ‘Rose Sensation’. Many Thunbergia varieties are conservatory/greenhouse plants when grown in the UK. T. erecta and T. battiscombii are good examples of Thunbergia that grow with a shrub habit and have attractive large blue flowers.
Not all Thunbergia have the distinctive blackeye, the species T. gregorii produces masses of pure bright orange flowers from April-December.
Thunbergia mysorensis (Indian Clock Vine) is probably the most spectacular of this genus. An evergreen vine native to tropical India, flowering on long racemes of red and yellow flowers which can reach up to 1.5m.