The Thunbergia grandiflora is a climbing plant with blue or sometimes lavender inflorescence which has the ability to grow considerably. A species that is commonly cultivated in all tropical regions, it is regarded as invasive in Singapore, the Seychelles, Hawaii and in some regions of the United States and Australia.
Thunbergia is a Genus named in honour of Swedish doctor and botanist Carl Peter Thunberg. Grandiflora means “with large flowers” in Latin.
Description and flowering period
It is a fast-growing vine which rapidly reaches up to 12 meters in height. The plant secures its hold onto neighbouring trees thanks to its twining stems and possesses a dense and tuberous rootstock as well as a deeply anchored tap-root. The persistent leaves vary greatly in shape (ovoid to heart-shaped, with either entire, toothed or even lobed margins). The flowers, either solitary or borne in terminal clusters, have a tubular corolla which is prolonged by 5 large (5 to 8cm) outward lobes. They are usually a pale lilac colour with a pale yellow throat but some cultivars (horticultural varieties) have white flowers (‘Alba’), deep blue flowers (‘Augusta Blue’) or lavender flowers with a darker throat (‘Antigua’). The vines only comes to fruit in the warmer climates. Its fruit is a spherical capsule with a pointed end and bears flattened seeds which are ejected away from the mother-plant when the capsule opens.
It requires a fresh, yet well-drained soil in a full sun or part-shade location sheltered from winds and frosts (zero frost tolerance). It is only suitable for warm climates.
The species is widely cultivated in tropical areas, it is now considered as invasive in some states of the USA, Singapore, Hawaii, the Seychelles as well as Australia.
Translated by: François Saint-Hillier – MNHN