Acacia gum exudates from species of the series gummiferae

An analytical study of the gum exudates from the African species Acacia ehrenbergiana (three specimens), A.xanthophloea (two specimens), A.hockii and A.sieberana var.villosa, and of the Australian species A.calcigera, has been made. There are now 19 species within the series Gummiferae Benth. for which gum parameters are available; of these, only A. ehrenbergiana gum displays a slightly negative optical rotation. The data for the three gum specimens from A. ehrenbergiana give a further example of the extent to which the gum from different trees of one particular species can vary in composition. The data for A.sieberana var. villosa gum are compared with the values established previously for subsp. sieberana; the differences between varieties of one species are similar in extent to those established for some subspecies. Although A. xanthophloea, A. hockii, A. ehrenbergiana, A. seyal and A. karroo are regarded as being very closely related botanically, the values for some of their analytical parameters differ considerably and strongly support the view that it is correct to retain them as distinct species.