Sweet thorn, cape gum, cape thorn tree, cockspur thorn, deo babool, karroo thorn.
Sweet thorn (Acacia karroo Hayne or Vachellia karroo (Hayne) Banfi & Galasso) is a very variable and very thorny tree species that is widespread in Africa and grows to a height of 5-12 m. It is a multipurpose tree providing food, feed, commercial products, and environmental services. Livestock and wild animals relish on its foliage, pods and seeds, which do not contain antinutritional factors.
Morphology
Acacia karroo is a very variable, thorny, evergreen or almost evergreen tree that grows to a height of 2-20 (-25) m. It has a rounded crown. The branches emerge rather low on the trunk. The bark is smooth and dark red on young branches, becoming rough or fissured and blackish on the trunk and on old branches. The leaves are alternate, pedunculated, bipinnate, bearing 2-7 pairs of primary pinnae each bearing 5-15 (-27) pairs of leaflets. Very long (up to 17 cm), straight, and conspicuous white spines are borne at the base of the leaf-stalk. The leaflets are 4-7 mm long x 1-3 mm broad. The flower-heads are axillary borne on young shoots and grouped in pompons. They are deep or golden yellow in colour. The flowers are ball-shaped. The fruit is a 18 cm long dehiscent pod, green to brown when mature. It is flat and has a crescent shape, constricted between the seeds. Pods split open at maturity. The seeds are small, 5-8 mm x 3-5 mm long, oblong-elliptic in shape, olive green to brown in colour (CABI, 2018; Aubrey, 2002; US Forest Service, 2018).
Uses
Acacia karroo is a multipurpose tree that can be used for food and feed, and yields useful products. The foliage and the pods are readily eaten by livestock and wildlife. They can be browsed or cut, and are reported to be deprived of antinutritional substances. The tree yields an edible gum similar to arabic gum and useful for candy production. The seeds can be roasted to make a coffee substitute. The flowers are attractive to bees and the long flowering period allows to produce pleasant honey from the nectar. Sweet thorn is a valuable source of fuelwood and charcoal. The timber is used to make posts and pens. The bark yields tannins used for dyeing leather to a reddish colour but also providing an unpleasant odour. The inner bark is used to make ropes. Sweet thorn provides environmental services (see Environmental impact)
