Most acacia trees are indigenous to South Africa, but not the Port Jackson willow, which was imported from Australia and is now considered a weed in Western Cape. In Australia the trees is called the wattle tree.

The best known acacia trees in Southern Africa are the thorn trees that grow on the savannahs.

Many of the trees have thorns and they have tiny yellow flowers. The trees are generally small, evergreen and fast-growing. They flower in late spring and early summer. This tree has large, sticky pollen grains, but they do not produce much pollen in South Africa and the pollen is not easily carried by the wind.

The pollen of some acacia trees can be toxic.