Thevetia peruviana (Yellow Oleander)

Scientific name

Thevetia peruviana (Pers.) K. Schum.

Synonyms

Thevetia neriifolia A. Juss. Ex Steud.; Cerbera thevetia L.; Cascabela thevetia (L.) Lippold

Common names

Yellow oleander, be still tree, digoxin, lucky nut, Nerium oleander, yellow bells

Family

Apocynaceae

Origin

Tropical America

Naturalised distribution (global)

Locations within which Thevetia peruviana is naturalised include many Pacific Islands

Introduced, naturalised or invasive in East Africa

Thevetia peruviana is naturalised in parts of Kenya (A.B.R. Witt pers. obs.) and invasive in parts of Tanzania (Henderson 2002) and Uganda (A.B.R. Witt pers. obs.).

Habitat

Thevetia peruviana can be found in pastures, in savanna and in riparian zones (banks of watercourses).

Description

Thevetia peruviana is a small ornamental tree which grows to about 1.5 - 2.3 m high.  The leaves are spirally arranged, linear and about 13-15 cm in length (Samal et al. 1992).

Flowers are bright yellow and funnel-shaped  with 5 petals spirally twisted. The fruits are somewhat globular,  slightly fleshy and have a diameter of 4-5 cm.  The fruits,  which are green in colour, become black on ripening.  Each fruit  contains a nut which is longitudinally and transversely divided.  All parts of the plant contain the milky juice.

Reproduction and dispersal

This plant reproduces by seed. Locally, it is also propagated by cuttings especially for use as a live hedge.

Economic and other uses

Thevetia peruviana is widely grown as a garden ornamental. It is also used medicinally to some extent, though it is also known to be very poisonous. This uses cannot compensate for this plant's overall negative impacts.

Environmental and other impacts

Thevetia peruviana can be invasive in open areas and under light shade. All parts of the plants are very poisonous, especially the sap and oily seeds. The common name be-still refers to its poisonous properties.

T. peruviana has been included in the Global Invasive Species Database (GISD 2010). It has been listed as a noxious weed in South Africa (prohibited plants that must be controlled. They serve no economic purpose and possess characteristics that are harmful to humans, animals or the environment).

Management

The precise management measures adopted for any plant invasion will depend upon factors such as the terrain, the cost and availability of labour, the severity of the infestation and the presence of other invasive species.

The best form of invasive species management is prevention. If prevention is no longer possible, it is best to treat the weed infestations when they are small to prevent them from establishing (early detection and rapid response). Controlling the weed before it seeds will reduce future problems. Control is generally best applied to the least infested areas before dense infestations are tackled. Consistent follow-up work is required for sustainable management.

The editors could not find any specific information on the management of this species.

Legislation

Not listed as a noxious weed by the state or governments in Kenya, Tanzania and Uganda.

References

Appa Rao, M., Venkata, E. and Visweswaram, D. (1978). Effect of certain structural changes in cardiac glycosides of Thevetia peruviana on their toxicity.  Journal of Molecular and Cellular Cardiology10 ( Suppl. 1): 86.

GISD (2010). Global Invasive Species Database online data sheet. Thevetia peruviana (tree). www.issg.org/database. Accessed March 2011.

Henderson, L. (2001).  Alien weeds and invasive plants. A complete guide to declared weeds and invaders in South Africa.  Plant Protection Research Institute Handbook No. 12, 300pp. PPR, ARC South Africa.

Pacific Island Ecosystems at Risk (PIER). Thevetia peruviana (Pers.) K.Schum., Apocynaceae: plant threats to Pacific ecosystems www.hear.org/pier/species/thevetia_peruviana.htm. Institute of Pacific Islands Forestry, Hawaii, USA. Accessed March 2011.

Samal, K.K., Sahu, H.K. and Gopalakrishnakone, P. (1992). Clinico-pathological study of Thevetia peruviana (yellow oleander) poisoning. Journal of Wilderness Medicine, 3(4):382-386.

Editors

Agnes Lusweti, National Museums of Kenya; Emily Wabuyele, National Museums of Kenya, Paul Ssegawa, Makerere University; John Mauremootoo, BioNET-INTERNATIONAL Secretariat - UK.

Acknowledgments

This fact sheet is adapted from The Environmental Weeds of Australia by Sheldon Navie and Steve Adkins, Centre for Biological Information Technology, University of Queensland. We recognise the support from the National Museums of Kenya, Tropical Pesticides Research Institute (TPRI) - Tanzania and Makerere University, Uganda. This activity was undertaken as part of the BioNET-EAFRINET UVIMA Project (Taxonomy for Development in East Africa).

Contact

BioNET-EAFRINET Regional Coordinator: eafrinet@africaonline.co.ke