Bleedwood tree (Pterocarpus angolensis)
|Also known as:||kiaat, mukwa, Transvaal teak|
|Size||Height: 5 - 20 m (2)|
Trunk diameter: 0.6 m (3)
The bleedwood tree is classified as Near Threatened (NT) on the IUCN Red List (1).
The tropical, deciduous bleedwood tree (Pterocarpus angolensis) is particularly beautiful when the small, sweetly-scented, orange-yellow flowers bloom in spring, and in autumn when the long, drooping leaves assume a dark yellow colour (3) (4). The bleedwood tree has a wide, flattened crown consisting of large leaves, 30 to 40 centimetres long and divided in a feathery manner. The trunk has handsome heartwood, varying in colour from light brown to red or coppery-brown (4), and bark that is dark, rough and cracked (3). The bleedwood tree’s seed pods are almost circular, with a hard centre covered in brown bristles, surrounded by a thin, creamy-brown wing (3). The pods can be up to ten centimetres in diameter and are borne in hanging clusters (4). The dark red, sticky sap from which the tree gets its name is used as a dye and has medicinal properties (3).
The bleedwood tree occurs in woodland areas of east and southern Africa, in Angola, Botswana, the Democratic Republic of Congo, Mozambique, Namibia, South Africa, Swaziland, Tanzania, Zambia and Zimbabwe (5)
The bleedwood tree occurs in dry, deciduous woodland and open bushveld, from 300 to 1,550 metres above sea level (2). It generally grows on well-drained terrain (4), most often in deep sandy soil (3).
For around two weeks in spring, the bleedwood tree bears abundant pretty, little flowers, at the same time as the new leaf buds begin to shoot (3) (6). By winter, the long drooping leaves have gone and the bleedwood tree is adorned with hundreds of its distinctive pods (3) (7). The paper-like wing of the pod enables it, and the one or two seeds within, to be carried on the wind away from the parent tree (4) (7). The hard, spiny centre of the pod does not split open on its own and thus requires physical abrasion or other mechanisms for it to open and allow the seeds to germinate (7). Exposure to moderate levels of fire has also been shown to assist in the breaking down of the woody pod, and therefore facilitate germination (8). Bleedwood trees are reproductively mature and produce pods (fruit) at 15 to 20 years of age (5), and continue to produce fruit until they die (6).
In some areas, bleedwood trees are becoming less common as they are heavily exploited by local people and for export (5). The handsome heartwood is one of the best timbers in southern Africa (3), one of the most favoured furniture woods, and is used extensively by artists producing sculptures of wild animals for the curio trade (4). In many parts of its range there is no control over the rate of harvesting (5). In addition, clearing of land for agriculture and housing, expanding human populations, and heavy browsing of small bleedwood trees, all play a part in this species’ continuing decline (2). Populations may also be impacted by the death of large bleedwood trees from a fungal disease (5) (9).
Despite the threats this species faces, large stands of the bleedwood tree still occur, particularly in protected areas in South Africa, Botswana and Namibia, and there are attempts to use these remaining stands in a sustainable way (5).
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- Bushveld: a habitat consisting ofextensive grasslands with scattered trees and bushes, found in the east of the interior of South Africa.
- Deciduous: a plant that sheds its leaves at the end of the growing season.
- Deciduous forest: forest consisting mainly of deciduous trees, which shed their leaves at the end of the growing season.
- Germination: the beginning of growth, usually following a period of dormancy and in response to favourable conditions. For example, the sprouting of a seedling from a seed.
IUCN Red List (March, 2011)
- Loots, S. (2005) Red Data Book of Namibian Plants. SABONET, Pretoria and Windhoek.
- Palmer, E. (1977) A Field Guide to the Trees of Southern Africa. William Collins Sons and Co Ltd, Glasgow.
- Van Wyk, P. (1993) Southern African Trees: A Photographic Guide. New Holland Ltd, London.
- Oldfield, S., Lusty, C. and MacKinven, A. (1998) The World List of Threatened Trees. World Conservation Press, Cambridge, UK.
World Agroforestry Centre: Agroforestree Database (December, 2007)
- Boaler, S.B. (1966) The Ecology of Pterocarpus angolensis D.C. in Tanzania. Overseas Research and Publication No. 12, Ministry of Overseas Development, London.
- Banda, T., Schwartz, M.W. and Caro, T. (2006) Effects of fire on germination of Pterocarpus angolensis. Forest Ecology and Management, 233(1): 116 - 120.
Tree Conservation Information Service (December, 2007)