Acacia tortilis (SA Tree List 188 and 188.1) has rough grey or brown bark, vertically fissured on mature specimens. The spines are variable on a theme of paired small curved hooks and straight white ones. The two spine shapes on the same tree help with identifying this species. Acacia luederitzii var. luederitzii also has hooks and straight spines, but its leaves are long, longer than 3 cm while A. tortilis leaves are shorter than 2 cm. The leaves have the typical Acacia bipinnate (twice compound) form. They are small, compact, closely ranked and blue-green in colour. There is a small gland immediately below the lowest pair of leaflets on the leaf stalk. The flowers are cream, white or dull yellow, hairy spheres, appearing in summer. The pods are densely twisted and spiralled into a ball.
There are several recognized subspecies of this tree, although mostly beyond South Africa’s northern border, the biggest part of the tree's habitat. The two that grow in South Africa are subsp. heteracantha with narrow pods and not hairy. Heteracantha means different thorns or spines. More hairs and wider pods, found commonly on river banks is A. tortilis subsp. spirocarpa (Coates Palgrave, 2002).