Acacia nilotica and Acacia karroo have a lot in common. Both normally show only 3-6 pair of pinnae (/whereas the above tree has 8 p/p). The characteristic difference normally is the fruit, which is darker, restricted between the seeds and shows pronounced seeds in A. nilotica. But from H. Ross (Conspectus...) we also know that A. nilotica is very variable. One subspecies shows a fruit a bit like the above: Acacia nilotica ssp. leiocarpa. As the tree seems to be natural, I opted for this ssp. rather than for an imported A. karroo.