The coarse, brown-grey bark of this Senegalia nigrescens tree is becoming fissured and cracking into rectangular patches.
It is, however, the large knobs on the stem and branches of the knob thorn tree that catch the eye. They may have disappeared from the lower parts of the main bole of an old tree, while not yet having formed on new growth at the top. On branches of medium thickness they are scattered in variable density, shapes and sizes. The knobs seen here have mostly lost the thorns that earlier grew on their tips (Carr, 1976; Coates Palgrave, 2002).