Jacaranda mimosifolia (Jacaranda)

Scientific name

Jacaranda mimosifolia D. Don

Synonyms

Jacaranda chelonia Grisb.; J. ovalifolia R. Br.

Common names

Jacaranda, mucakaranda (Kikuyu), omosaria (Kisii), fern tree

Family

Bignoniaceae

Origin

Native to South America (southern Bolivia and north-western Argentina).

Naturalised distribution (global)

Locations within which Jacaranda mimosifolia is naturalised include the warmer parts of eastern Australia, southern Africa, Hawaii, south-eastern USA and outside its native range in southern South America.

Introduced, naturalised or invasive in East Africa

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

Habitat

Jacaranda mimosifolia can grow in bushland, grassland, wooded ravines and riverbanks. The spreading growth habit and the dense foliage shade out native plants and prevent their regeneration.

Description

Deciduous or evergreen tree, 5-15 m tall. Its main distinguishing feature is its spectacular lavender blue blooms which has led to its popularity as an ornamental tree. Jacaranda mimosifolia is fast growing and resprouts easily if damaged.

Its bark is thin and grey-brown in colour, smooth when the tree is young though it eventually becomes finely scaly. The twigs are slender and slightly zigzag; they are a light reddish-brown in colour. Twice-pinnately compound leaves, up to 45 cm long.

Its flowers are beautiful, lavender blue, tubular, 2.5 cm long, appear in dense 15 - 25 cm terminal clusters with often the entire tree in flower and later the ground turning blue as the flowers fall off. Round, flat, reddish brown, woody capsule, 4 - 5 cm in diameter containing numerous small winged seeds.

Economic and other uses

Its main value is as an ornamental tree widely grown in urban areas worldwide. It also has medicinal properties. However, these uses cannot compensate for this plant's overall negative impacts.

Environmental and other impacts

Jacaranda mimosifolia is regarded as an invasive species in parts of South Africa and Queensland, Australia, where it can out-compete native species. It can form thickets of seedlings beneath planted trees from which the species may expand and exclude other vegetation.

J. mimosifolia has been listed as a Category 3 invader in South Africa (no further planting is allowed - except with special permission - nor is trade in propagative material. Existing plants must be prevented from spreading).

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. Some components of an integrated management approach are introduced below.

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.

Jacaranda mimosifolia is very difficult to control once established. Large trees must be ring-barked or cut down below ground level and any regrowth treated with herbicide. . When using any herbicide always read the label first and follow all instructions and safety requirements. If in doubt consult an expert.

Legislation

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

References

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.

Henderson, L. (2002). Problem plants in Ngorongoro Conservation Area. Final Report to the NCAA.

Pacific Island Ecosystems at Risk (PIER). Jacaranda mimosifolia D.Don, Bignonaceae: plant threats to Pacific ecosystems. www.hear.org/Pier/species/ jacaranda_mimosifolia.htm. Institute of Pacific Islands Forestry, Hawaii, USA. Accessed March 2011.

Wikipedia contributors. "Jacaranda mimosifolia." Wikipedia, The Free Encyclopedia. Accessed March 2011.

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