If you were a game or stock farmer with browsers on your property, this lovely Acacia species would be an asset to you. Please just remember the pods are said to be toxic to goats.
A medium to large tree that can reach a height of 10 m, with an average of 4-7 m in height. The crown is somewhat flattened or rounded, with a moderate density. The branches have a tendency to droop downwards if the crown is roundish. The bark is blackish grey or dark brown in mature trees and deeply grooved, with longitudinal fissures. The young branches are smooth and grey to brown in colour. The young twigs are covered in short hairs. Paired, slender, straight spines grow from a single base and sometimes curve backwards, are up to 80 mm long and whitish but often reddish brown in colour.
The leaves are twice compound, i.e. they consist of 5-11 feather-like pairs of pinnae; each pinna is further divided into 7-25 pairs of small, elliptic leaflets that can be bottle to bright green in colour. The leaf stalks are heavy. Very small glands, almost not noticeable with the naked eye, can be found at the base of most of the upper pinnae pairs.
It bears single to several, bright, golden yellow, globose, scented inflorescences between the leaves. The flower stalks are hairy. It flowers mainly from September-January, but it depends on the rainy season. The pods are very characteristic, resembling a beaded necklace. The pods are flat, straight or slightly curved, and fleshy when young with reddish hairs, becoming dark blackish when mature, deeply constricted between each seed and they do not split open, but break up transversely on the ground into single-seeded segments during March to September. The pods are sweetly scented when crushed and contain a sticky fluid.
Distribution and Habitat
This tree occurs in a variety of woodland types, wooded grassland and scrub escarpment, forests and low-lying forest, in deep soil and along rivers. It is found in large areas of KwaZulu-Natal , Swaziland , eastern and northern Mpumalanga , the northern part of Gauteng , throughout Limpopo and the northeastern part of the North-West. This subspecies occurs south of the Zambezi River.
Derivation of name and historical aspects
Acacia is from the Greek word akis meaning sharp point, nilotica refers to it occurring along the Nile River , and kraussiana refers to Dr Christian Ferdinand Friedrich von Krauss (1812-1890), a German biologist and professor at the University of Stuttgart who travelled and collected in South Africa .
Uses and cultural aspects
The wood of this species is hard and reddish in colour and most of the browsers eat the leaves. It is used as firewood and for fencing posts. The bark exudes an edible gum and is used medicinally according to Van Wyk et al. (2000). The gum can also be used as glue. The Zulus take a decoction of the bark as a cough remedy. The Voortrekkers made ink and dyes from the pods (red, black and yellow). Other parts of the tree were used to treat eye diseases, or as a tranquillizer and even as an aphrodisiac. A root extract was used in the treatment of tuberculosis, impotence, diarrhoea, haemorrhages, toothache, dysentery and gonorrhoea. Extracts made from the leaves are used in the treatment of menstrual problems, eye infections, sores (specifically those caused by leprosy), ulcers, indigestion and haemorrhage.
Growing Acacia nilotica subsp. kraussiana
This medium to large semi-deciduous tree will grow in most gardens although slightly frost tender. It is very drought resistant. It can easily be grown from seed. Please ensure that the seeds are cleaned properly. They can be slightly scarified or left in hot water for a few hours or overnight. For best results sow seed in separate bags as it develops a taproot very quickly. Seed normally germinates reasonably fast within 7-15 days. The trees are slow growing.
References and further reading
- Coates Palgrave, K. 1990. Trees of southern Africa . Struik, Cape Town .
- Davidson, L. 1981. Acacias, a field guide to the identification of the species of southern Africa . Centaur Publishers, Johannesburg .
- Thomas, V. & Grant, R. 2004. SAPPI tree spotting: KwaZulu-Natal and Eastern Cape . Jacana, Johannesburg .
- Van Wyk, P. 1990. Veldgids tot die bome van die Nasionale Krugerwildtuin . Struik, Cape Town .
- Van Wyk, B. & Van Wyk, P. 1997. Field guide to trees of southern Africa . Struik, Cape Town .
- Van Wyk, B., Van Wyk, P. & Van Wyk, B-E. 2000. Photographic guide to trees of southern Africa . Briza Publications, Pretoria .
- Venter, F. & Venter, J.A. 1990. Making the most of indigenous trees . Briza Publications, Pretoria .
Pretoria National Botanical Garden