Morphological and anatomical development in the Vitaceae.: X.: Comparative ontogeny and phylogenetic implications of Cissus quadrangularis L.

Although the grape family, Vitaceae, is of great economic importance, there is little understanding of the relationships between and within the genera. Recent DNA-based phylogenies of the Vitaceae have disagreed with traditional classifications by grouping some Cissus species (e.g., Cissus antarctica Vent.) in a clade with Vitis species, while placing other Cissus species (e.g., Cissus quadrangularis L.) in a monophyletic clade. This study investigates Cissus phylogeny using epi-illumination light microscopy and histological ontogenetic comparisons of vegetative and reproductive characters of Vitis rotundifolia (Forssk.) Vahl. Vitis 'Ventura'. Vitis riparia Michx., C. antarctica, and C. quadrangularis. Ten characters limited to the Cissus species (connection of stipules, precocious axillary bud initiation, prophyll growth not obviously unequal, timing of mature shoot architecture on axillary buds, lack of spiral inflorescence branching. absence of calyptra, petals closely enveloping anthers, large gynoecial disk, ovary buried in the disk, and production of copious amounts of nectar) support the traditional phylogenies: the monophyly of Vitis and the exclusion of Cissus species 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.