Senegalia nigrescens leaves in their prime

These healthy leaves of Senegalia nigrescens have fairly short, yellowish stalks. Leaves grow solitary or in pairs at the nodes, sometimes on fairly long stalks of up to 8 cm, when stimulated by good rain.

Each twice-compound leaf carries one to four pairs of pinnae, commonly three. Each pair of pinnae in turn comprises one or two pairs of pinnules. These leaflets or pinnules are obliquely obovate, but may in this species be almost circular and characteristically large; the largest pinnules seen on any South African Sengalia species.

Leaflet colour is grey-green or blue-green (glaucous), paler on the lower surfaces. The midribs of the pinnules, as well as some secondary venation, are clearly visible. Small prickles are sometimes found on the stalks of the pinnules, the rachillas.

In the photo the reddish colour of the curved young thorns or spines can be seen. Old thorns are black. A dense covering of small white lenticels is visible on the young twig (Carr, 1976; Coates Palgrave, 2002).