Vachellia karroo spines and leaves

The leaves of Vachellia karroo are bipinnate, varying much in the number of pinnae and pinnules. The individual leaflets or pinnules are oblong with rounded tips. The rachis is grooved with glands between some of the pairs of pinnae.

The spines are straight, white and strongly developed with dark tips. They are sometimes swollen and may become up to 10 cm long.

The presence of sweet thorn trees in arid places is often an indicator of underground water. The long taproots of these trees are bound to find available moisture, which remains beyond reach of the shorter rooted scrub and grasses growing around it and flourishing seasonally (Coates Palgrave, 2002).