Chromosome numbers were surveyed in populations of Acacia karroo Hayne and A. tortilis (Forssk.) Hayne sampled across their wide geographical range. Only one cytotype, with a chromosome number 2n = 52, was found in populations of A. karroo and A. tortilis subspecies tortilis, spirocarpa and heteracantha. Both 2n = 52 and 2n = 104 were found in populations of A. tortilis subspecies raddiana. It was concluded that most common morphological varieties of A. karroo and A. tortilis subspecies tortilis, spirocarpa and heteracantha are tetraploids, but the possibility of isolated cases of other cytotypes cannot be excluded given that naturally sterile trees have been documented previously in A. karroo. The cytotypes of A. tortilis are more variable. Clarification will require more detailed analysis.
Oballa, P.O.; Olng’Otie, P.A.S. Chromosome numbers in two African Acacia species. Kew Bulletin (1993) 49 (1) 107-113.