Recent DNA-based phylogenies of the grape family (Vitaceae) have disagreed with traditional classifications by grouping some 'Cissus' species (e.g. 'C. antarctica') in a clade with 'Vitis ' species, while other 'Cissus' species (e.g. ' C. quadrangularis') formed a monophyletic clade. In fact, ' V. rotundifolia' was more closely linked with the 'Cissus' species than with the 'Vitis' species. The objectives of this study were to clarify 'Vitis' and 'Cissus' phylogenies using ontogenetic comparisons of vegetative and reproductive characters of ' V. rotundifolia, V.' cv. Ventura, 'V. riparia, C. antarctica, ' and 'C. quadrangularis.' Ten characters limited to the 'Vitis' species support the traditional phylogenies: the monophyly of 'Vitis' and the exclusion of 'Cissus ' spp. from 'Vitis.' The comparison of 'C. antarctica ' ('Vitis-Cissus' clade) and 'C. quadrangularis ' (monophyletic 'Cissus' clade) supports the division of 'Cissus' into two clades based on supernumerary buds, stipule connectivity, uncommitted primordium shape, and inflorescence branching patterns.