The composition and properties of gum exudates from subspecies of Acacia tortilis

Gum specimens from Acacia tortilis ssp. spirocarpa, ssp. raddiana var. pubescens (two specimens) and ssp. heteracantha (three specimens) have been analysed. The results are of chemotaxonomic interest. Although the gum from ssp. raddiana var. pubescens appears to be intermediate between those from ssp. spirocarpa and ssp. heteracantha in terms of some of the analytical parameters, the overall impression is that ssp. raddiana is more similar chemically to ssp. spirocarpa than to ssp. heterocantha. The latter yields a viscous, proteinaceous polysaccharide that differs from those from both ssp. spirocarpa and ssp. raddiana by having a much higher ratio of arabinose to galactose, higher nitrogen and methoxyl contents, and much higher intrinsic viscosity and molecular weight; preliminary experiments have shown this gum to consist of two components.