Gigi just sent me an interesting link to DWAF's Champion Trees Project
The Department of Water Affairs and Forestry (DWAF) initiated a project to identify and protect trees worthy of special protection throughout South Africa. Such projects have been established in several countries, but this is the first of its kind in Africa. Champion trees are trees of exceptional importance that deserves national protection because of their remarkable size, age, aesthetic, cultural, historic or tourism value.
I see there is also info on protected trees here and you can download the latest list of protected trees here as a pdf file.