The black thorn (Acacia mellifera (M. Vahl) Benth.) is an African shrub or small tree growing to a height of 9 m. It has an extensive root system that explores large volumes of soils, allowing survival in dry areas. It has a tangled, balled-shaped or flat-topped canopy that may reach down to ground level. The branches bear pairs of black hooked thorns every 5 to 15 mm. The leaves are bipinnate with only 1-2 (-4) pairs of pinnae each bearing 1-2 (-3) pairs of ovate or obovate leaflets. Leaflets are 3.5-15 mm long x 2-12 mm broad. Initially green, black thorn leaves become glaucous with maturity. The flowers are fragrant, sweetly scented, 3-5 cm long and creamy white in colour, borne in dense hanging spikes. The fruits are straw coloured flat pods, 3-8 cm long x 1.5-2.5 cm wide, that contain three seeds. The tree lives less than 10 years (FAO, 2014; Nonyane, 2013; Orwa et al., 2009; Hines et al., 1993).
The black thorn is a multipurpose tree. The leaves, pods and young shoots are nutritious and make fodder for livestock and wild animals. They are browsed by camels, goats and wild animals such as black rhinos, kudus, elands and giraffes. Goats are particularly fond of the leaves, which may constitute a considerable part of their diet. Fallen browse, dry leaves and pods are eaten on the ground by cattle and sheep who, unlike camels and goats, are less likely to browse them. The flowers are attractive to bees, which produce a high quality honey, hence the name mellifera. The timber is hard, almost black when polished, resistant to termites and used for construction and fencing. Black thorn trees are used for live fencing and hedging (FAO, 2014; Nonyane, 2013; Orwa et al., 2009; Hines et al., 1993). The bark is used in ethnomedicine to treat stomach problems, sterility, pneumonia, malaria and syphilis (Rulangaranga, 1989 cited by Hines et al., 1993).
