The Knobthorn (Acacia nigrescens) is a slow-growing, medium to tall tree reaching heights of between 10-65 feet. It is found growing from the wooded grasslands of the Lowveld in Southern Africa to as far north as Tanzania, surviving in many different soil types. The tallest trees of this species are always found on flood plains. The Knob-thorn has a straight, upright trunk, with ascending branches forming a rounded canopy that spreads with age. The bark is dark and thickens, forming knobs equipped with small black hooked thorns. These thorny knobs are prominent on the newer branches of mature trees and on the trunks of young trees, offering some protection against browsing animals such as elephants. The knobs are very conspicuous, making the Knob-thorn tree easy to identify.