This beautiful tree is the most common naturally occurring acacia in the Witwatersrand National Botanical Garden. It may reach up to 14m and has an irregular, spreading crown. In some habitats it remains as a shrub. One of the most attractive features of the tree is the foliage which is bright green and feathery looking. The leaves are drooping which gives the canopy a lovely soft look.

The name Acacia is derived from "akis " meaning a point or barb and caffra was a epiphet frequently bestowed on plants from the eastern parts of South Africa in previous centuries. The word caffra in Hebrew means "person living on the land".

The Acacia caffra occurs naturally in a wide variety of habitats from coastal scrub to bushveld and highveld grasslands. The distribution appears to be slightly patchy with the species occurring in the four northern provinces; the coastal areas of Kwazulu Natal and the Eastern Cape and in some areas of the Western Cape. Another interesting feature of the tree is its tolerance of low soil pH which occurs where the soils are sandy and the rainfall is high. The Acacia caffra is able to withstand fire, which is important in areas such as grasslands and savannas where fire forms an integral part of the ecology.

The tree is deciduous and is one of the first to shoot in spring. The new leaves are particularly pretty, being a soft, fresh green. The flower spikes are creamy white and sweetly scented. They appear from September to November with the main flowering occurring in October. The flower spikes are large and conspicuous and make a lovely show against the backdrop of the new leaves. They are followed by narrow, straight, brown seeds pods.

The Van Son's Playboy (Deudorix vansoni) and Pennington's Playboy (D. penningtoni) butterflies breed in galls on the branches of the tree. The wood is dense and hard and beautifully grained. The foliage enjoyed by game and stock. The common hook-thorn is used traditionally for many purposes such as fencing posts, tanning and the beautiful rootwood is highly valued by Xhosa women for tobacco pipes. It is also used medicinally and is considered a lucky tree in traditional African beliefs.

Growing Acacia caffra

The trunk is very often crooked which gives the tree wonderful character in a garden. It is frost and drought resistant and has a growth rate of about 700mm - 900mm per year. Like other Acacia species the common hook-thorn throws a light shade which allows enough light through to enable lawn to grow beneath. Acacia caffra has a stately shape and looks very elegant in a sweep of lawn. It responds well to pruning. Avoid planting near paving or buildings as it reportedly has an aggressive root system.

It grows easily from seed. The seeds need hot water treatment before they will germinate. Simply pour hot water over them and allow to cool. You will see if this has worked as the seeds will begin to swell as they absorb water. Do not leave them in the water for longer than 24 hours or they will start to deteriorate. It is best to sow directly into black bags as the taproot is long and is sensitive to transplanting.

References:

• Henning, G.A, Henning, S.F et al. 1997. Living Butterflies of Southern Africa, Vol. I. Umdaus Press. Pretoria.
• Pringle, E.L.L., Henning, G.A., Ball, J.B. (eds) 1994. Pennington's Butterflies of Southern Africa. 2nd Edition. Struik. Cape Town.
• Smit, N. 1999. Guide to the Acacias of South Africa. Briza Publications. Pretoria
• Thomas, V and Grant, R. 1998. Sappi Tree Spotting, Highveld and the Drakensberg. Jacana Education. Johannesburg.
• Van Wyk, B and van Wyk, P. 1997. Field Guide to Trees of Southern Africa. Struik Publishers. Cape Town.
• Venter, F and J-A. 1996. Making the most of Indigenous Trees. Briza Publications. Pretoria.

Alice Aubrey
Witwatersrand National Botanical Garden
September 2001