Are you certain this is sweetgum (Liquidambar)? The two common species in commerce (American and Oriental sweetgum) have leaves that are vastly different than these -- which look EXACTLY like Acer rubrum (Though how any of the sweetgum or the American red maple would get to S. Africa, I don't know).
Def a Sweetgum seedling, I have a bunch same size little bigger maybe, and up to 6' BnB.I have a sweet gum in my backyard and it gets suckers on the roots all year long. This is consistent with the first few leaves of a sweet gum. As the next few sets of leaves emerge and get larger you will find that they will look more like the typical sweet gum 5 lobed leaves.
Well things could be different around the world, but here are Sweet gum seedling leaves.What I have found on the net is that a sweetgum has no serrated edges where the red maple has