The genus Adenia (Passifloraceae) provides a model system with which to investigate the relationship between growth form and phytochemistry. With ca. 90 species the genus has a diverse and varied pharmacopoeia and at least seven distinct growth forms. An association between growth form and chemistry is expected based on theoretical predictions. I mapped cyanogenesis on the phylogeny of Adenia to reveal that 4 of the 5 putative shifts from ancestral tendrillate vines to growth forms without tendrils are in association with low cyanogenesis as expected. The phylogeny based on ITS sequence data and an extensive sampling of African and Madagascan species of Adenia supports 5 main lineages. Extrafloral nectary superstructure in large part supports the molecular characterization. Individuals in the most basal lineage of Adenia all possess spatulate glands at the leaf blade base. The next most ancient lineage has members that are tuberous vines and herbs. Members of this lineage share paired and upturned glands at the petiole-blade junction. A more recent lineage contains a wet-tropical African lineage and a dry-habitat African and Madagascan lineage. The wet-tropical lineage has lianas and vines with paired auriculate glands at the blade-petiole junction. The dry-habitat African and Malagasy lineage possesses species with succulence and often slightly recessed glands at the base of the leaf (although some Madagascan species are autopomorphic). The lineage that is sister to this more recent branch is least characterized by gland structure, but possesses a diversity of gland structures and growth forms. Research is underway to relate anatomical features with phytochemistry to rigorously test whether changes in anatomy (hence changes in growth form) are correlated with changes in phytochemistry.

Key words: Adenia, Africa, cyanogenesis, growth form, Passifloraceae, phylogenetics