Aristolochia gigantea. Although the flowers of Aristolochia are highly specialized whereas those of Lactoris are less complex, recent phylogenetic analyses based on molecular data suggest an unexpectedly close relationship between the two genera. Stipule ontogeny and morphology are essentially the same in Piperaceae, Saururaceae, and Lactoris, while inflorescence morphology is very similar in Lactoris and Aristolochiaceae. See Gonzalez and Rudall: The questionable affinities of Lactoris: evidence from branching pattern, inflorescence morphology, and stipule development, pp. 2143-2150 in thisissue.