The Acacia is the quintessential African tree. Commonly known as 'thorn trees', Acacias are associated with a typical African landscape.
The genus worldwide has about 1377 species, distributed throughout the tropical and warm temperate areas. Recent taxonomic research has pointed to the fact that the genus cannot continue to be maintained as a single entity. A contentious decision was made at the International Botanical Congress in Vienna in 2005 to rename the African species of the genus and this was hotly supported by Australian botanists. Author Nico Smit comments in an introductory piece on the proposed name change of the African genus Acacia that after this somewhat ambiguous decision made in Vienna, the end-users of plant names still have the choice as to whether they want to use the name Acacia in a strict or wide sense. The consensus in South Africa is overwhelmingly for the continued use of the name Acacia for the African species of the genus.
the original Guide to Acacias of South Africa by the same author was published in 1999 and a significant component of the material in that book has been included in this new publication. The book gives an account of all 48 recognised species, subspecies and varieties of the genus Acacia that occur within the borders of South Africa.
The National Tree Number is included for each species. It serves as a handy bold means of marking trees for recognition from a distance. Two pages are devoted to each form and each is illustrated by photographs of the architecture of the tree, its pods, bark, leaves, flowering heads and thorns. A distribution map and concise description, detailing the habitat, general appearance, main stems, shoots, thorns, leaves, inflorescence, pods and seeds, for each form is included. The species are divided into five groups based on the shape and position of the thorns.
Four newly described species are included in the field guide, along with four species which previously formed part of the Acacia karroocomplex. The new species are: A. sekhukhuniensis (Sekhukhune Thorn) which is known only from an isolated, flat-toped quartzite mountain near the north-eastern boundary of Sekhukhuneland; A. ebutsiniourum (Ebutsini Thorn) is known only from a single population north-east of Oshoek in Mpumalanga; while A. robbertsii (Hairy Sekhukhune Thorn) is found only in a small area near Steelpoort on the boundary of Sekhkhuneland.