Indigenous knobthorn tree
Scientific name: Acacia nigrescens - Senegalia nigrescens, Hook thorn group (574)
Acacia nigrescens is native to Tanzania southward to north-eastern Namibia, Botswana and north-eastern South Africa. The tree occurs in woodland and bushland, commonly near rivers, up to 1200(–1600) m altitude. It usually grows on shallow soils on rocky hillsides and on alluvial soils in the valleys. It is often common, locally dominant on loamy soils, and is resistant to fire.
Medium to large, deciduous tree. Bark dark brown to almost black. The trunk and main branches often covered in numerous knobs,tipped with a hooked prickle. Thorns strongly hooked, in pairs at the nodes. Leaves with 2-3 pairs of pinna, each with only 1-2 pairs of oval to near-circular leaflets. Flowers in long spikes, white, sweetly scented, appearing in great profusion before the leaves.
In Zimbabwe make an ointment from burnt roots to treat convulsions while in Tanzania a root decoction is used as an aphrodisiac.
Dietary fiber 8 g. Protein 2.45g. Carbohydrate: 75.03 g. Dry matter 93.3%. Energy (kg1,178) 282. Phosphorus 62mg. Calcium 39mg. Magnesium 43mg. Potassium 656mg. Iron 1.02mg.
The wood is used for parquet flooring, carving, turnery, fence posts, railway sleepers and mine props. It is occasionally made into furniture, although it is usually considered too heavy for this purpose. The bark is used for tanning.
The foliage is browsed by livestock. Cattle and various animals feed off the fallen leaves and pod. It provides shade for animals.