Gardeners, travellers and anyone interested in nature and ecosystems would find something useful in one or both of
these excellent guide about the trees of Southern Africa. In both cases the authors, Braam van Wyk and Piet van Wyk (not related, despite their shared surname) share some of their wealth of knowledge about the trees of our sub-continent.
The Pocket Guide to Trees of Southern Africa is small and light enough to carry around wherever you go, and would live well in your backpack, while being very useful as a quick reference to some of the most noticeable trees when deciding about trees to plant in your garden. Building on that is the 730-page, much more comprehensive Field Guide to Trees of Southern Africa that looks at 815 of the most common and naturalised alien tree species in southern Africa (about half of the total number of trees of our botanically diverse part of the world).
Field Guide: ISBN 978-1-77007-911-3, Struik Nature
Pocket Guide: ISBN 978-1-92057-202-0, Struik Nature