Bengal Clock Vine

By Morag Flight

Scientific name; Thunbergia grandiflora

In Zimbabwe, the flower commonly known as the Bengal Clock Vine or the Blue Sky Flower is frequently grown. It is a long lived perennial climbing plant best grown on a tree or against a fence. The young green stems are hairy and become thicker and browner as they mature. The leaves are bright green in colour and are quite large, varying from 8 to 22cm long and up to 15cm wide.  The 3-8cm long flowers are trumpet-shaped and are borne in clusters on long drooping branches. They have five pale blue, violet or mauve coloured petals and a pale yellowish or white throat.  

The Bengal Clock Vine fruit is a capsule with a rounded base about 18mm long. Interestingly, they only fruit when conditions are very warm. The seeds are quite fascinating in that they are smooth on one side and warty on the other.  They are mainly reproduced by seed when the pod splits and catapults the seeds several meters. There has been some success in growing this climbing plant from stem fragments or parts of the tuberous roots. It is widely grown as an ornamental or hedging plant. You do need to be careful as it is very vigorous and can smother other vegetation. The tubers can also cause damage to paths and building foundations if not controlled.  In 2010 it was listed on the Global Invasive Species. They are vulnerable to red spider mite and aphids but are generally disease-free.

Also commonly found in Zimbabwe in the Thunbergia species is the Black Eyed Susan (Thunbergia alata). It is the yellow one with the black eye in the middle. Although it is not indigenous to Zimbabwe, it is frequently grown.

Black Eyed Susan Vine

Images provided by Morag Flight and Pixabay

First published by Morag Flight on Ndeipi magazine issue 102.

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