Evidence is presented to suggest the hybrid origin of Aloe broomii, with the one putative parent belonging to Aloe series Purpurascentes and the other a member of Aloe series Anguialoe. A chemotaxonomic and morphological assessment is presented for both infrageneric groups and their hypothesised hybrid. Four of the species belonging to the series Purpurascentes display a characteristic leaf exudate profile containing the chemotaxonomic marker microstigmin. Aloe gariepensis and A. succotrina lack the diagnostic leaf exudate compounds. The distinct morphological apomorphies for Aloe section Anguialoe are supported on the chemical level reinforcing the monophyly of this group.