BACKGROUND: Not only does leaf shape vary between Passiflora species, but between sequential nodes of the vine. The often profound changes in leaf shape within Passiflora vines reflect the temporal development of the shoot apical meristem from which leaves are derived and patterned, a phenomenon known as heteroblasty. METHODS: Here, we continue a morphometric analysis of more than 3,300 leaves from 40 different Passiflora species using two different methods: homologous landmarks and Elliptical Fourier Descriptors (EFDs). RESULTS: Changes in leaf shape across the vine are first quantified in allometric terms; that is, changes in the relative area of leaf sub-regions expressed in terms of overall leaf area. The ability of different nodes to predictively discriminate species and the variability of landmark and EFD traits at each node is then analyzed. Heteroblastic trajectories, the changes in leaf shape between the first and last measured leaves in a vine, are then compared between species in a multivariate space. DISCUSSION: Leaf shape diversity among Passiflora species is expressed in a heteroblastic-dependent manner. Leaf shape between species and across the heteroblastic series is constrained by allometric relationships. The first leaves in the series are not only more similar to each other, but are also less variable across species. From this similar, shared leaf shape, subsequent leaves in the heteroblastic series follow divergent morphological trajectories, creating the disparate shapes characteristic of Passiflora leaf shape diversity.