Vachellia  tortilis subsp. tortilis reaches heights of between 5 and 20 m in nature. It is fairly slow-growing and in cultivation reaches a final height of between 3 and 5 m with a spread of 8-13 m. In extremely arid conditions, it may occur as a small, wiry bush.

The bark on the trunk is rough and varies from medium grey to almost black, with somewhat tortuous longitudinal fissures. On main branches the covering is dark and fissured. Branches about 40 mm in diameter are a dark grey with occasional blackened fissures here and there. Branchlets about 10 mm in diameter vary from olive green to brown or purplish. There are some interesting variations in the armature.

The thorns are in pairs at nodes which may be spaced at as little as 5 mm near tips, but up to 10-20 mm further down. Straight and hooked thorn pairs usually alternate at consecutive nodes, but a pair may comprise one hooked and one straight thorn.

There are usually from 2-6 leaves per node. In any such group there may be one or two major leaves, but often all are the same size. The leaf stalk length can be up to 30 mm but is ordinarily only half this dimension or even less. Both petiole (leaf stalk) and rachis (central axis of a compound leaf) are green and pubescent. There is, in most cases, a green or brown, domed or cupped gland on the petiole immediately below the first pinna pair (pinna = primary division of a compound leaf).The rachis is grooved on top, has inconspicuous raised dark glands at 2 or 3 or even more of the distal pinna junctions and ends in a short and rather blunt mucro. Pinna pairs vary, as a rule, from 4-10 in number, the average being 6.

There are up to 4 flower heads per node. They are globose, cream to white, scented and somewhat inconspicuous unless flowering happens to be profuse. The peduncle (stalk of the inflorescence) is about 13-14 mm long, slender, pubescent and has an involucel (a group of bracts) located at approximately one-third of the length up from the base. Flowers usually appear about midsummer but have been observed as late as February. Timing is probably largely dependent on the climate.

The fruits (pods) of this species cannot be confused with those of any other South African Vachellia or Senegalia. They are rolled up into a tight circle or wound into a helix of three or four turns, like a coil spring. The width is about 8 mm and the length of a helically coiled pod of three turns was calculated at 125 mm.They are longitudinally venose (veined), somewhat woody, usually glabrous and dry out to a light khaki colour.They occur in bunches and are indehiscent (not opening when ripe). Pods contain up to 14 seeds, some of which often do not mature. The seeds are well rounded, ellipsoid in outline, with face dimensions about 5,5 x 4 mm, greenish brown with a dark brown horseshoe-shaped areole (a distinct area on the face of a seed).