Acacia karroo Hayne – Sweet-thorn
Karoo thorn. Small tree. Distribution Southern Angola, east to Mozambique, south to South Africa. This tree is festooned with fearsome thorns, and, just before the rainy season starts, it produces poisonous sap
the slightest graze from a thorn at this time causes swelling and pain for several days. The bush people of the northeast district of Namibia use its sap in an arrow poison, adding it to the larva of Diamphidia – which is also poisonous. Its active ingredients are cyanogenic glycosides – which produce cyanide on hydrolysis. The bark contains tannins, which have been implicated in carcinogenesis. Acacia karoo produces Cape Gum, which is used in pharmaceutical preparations and to treat diarrhoea. Used to make rope from the bark, gum to make candy, fodder for animals, charcoal. Photographed in the Medicinal Garden of the Royal College of Physicians, London.
