There are four Acacias belonging to the “climbers”. They vary from multistemmed scandent shrubs to single stemmed trees:
Acacia ataxacantha, Acacia brevispica, Acacia kraussiana and Acacia schweinfurthii.
All of them show unpaired, recurved prickles scattered along the internodes, distinguishing them from the species with stipular spines and thorns.
All four have white to creamy flowers, three with globose flowering heads and only one, A. ataxacantha, the Flame Thorn, featuring abundant long flowering spikes, attracting scores of beetles and other insects.
It may be confused with Adenopodia spicata (Mimosoidae), which grows in the same area and resembles in climbing habit, prickles and leaves. The flowerspikes are, however, composed of flowers with only nine stamens, and the fruit is broader and clearly divided between seeds.
A. kraussiana, the Coast climbing Thorn, has smaller leaves than A. ataxacantha and globose flowering heads. Some shoots are modified into tendrils, which help in climbing.
It is more difficult to distinguish between the other two species with white to creamy globose flowering heads:
A. schweinfurthii, the river Climbing thorn, and A. brevispica, the Prickly Thorn. Both grow along the KwaZulu Natal coast. While A. brevispica extends more to the South, A. schweinfurthii can also be found near the Zimbabwean border.
J. Hurter considers A. brevispica more a “crawler” than a “climber”. In the identification guide on SA Acacias by Marthinus Steyn, they differ in the color of striations:
In A. brevispica, the hook-thorns are scattered on pale (grey) longitudinal ridges, while in A. schweinfurthii, prickles are scattered on dark longitudinal ridges.
J.D. Carr notes (in South African Acacia) that the foliage of A. brevispica is somewhat open in appearance and yellowish-green in color, as compared with the dark green of A. schweinfurthii.
N. Smit mentions, that the leaf of A. schweinfurthii shows a distinct elongated swelling at the base of the petiole and immediately above the swelling is a large, elongated yellow or dark coloured petiolar gland. There is occasionally a further doomed, yellowish gland on the petiole, about two thirds of the distance from the end of the swelling to the first pinnae pair. There is no second petiolar gland mentioned with A. brevispica.
2 petiolar glands
N. Smit also writes, that in A. schweinfurthii, the venetion on the backside of the leaflets is visible, whereas no such feature is mentioned for A. brevispica.
One has probably to look at many of the plants, before being able to distinguish with certainty between them.