XVI International Botanical Congess

One of the most significant advances in current understanding of angiosperm phylogeny is the recognition of the eudicot clade, which encompasses a significant portion of angiosperm taxonimic diversity and morphological disparity. Most eudicot floral disparity is constructed on a ground plan the most salient features of which are the presence of a single whorl of sepals and a single whorl of petals, a fixed merosity, and alternation in the radial placement or organs o adjacent whorls. Phylogenetic analyses of morphological data for living and structurally preserved fossil, and of combined morphological and molecular data (3 molecular data sets) for living taxa provide a significantly enhanced understanding of relationships at the base of the eudicot clade, and a solid framework in which the evolution of floral from is addressed. Phylogenetic analyses strongly suggest the eudicot floral ground plan is not a shared-dirived feature of eudicots s a whole, but rather, that it became assembled once within the clade. Integration of information from extant and fossil taxa in phylogenetic framework provides a context to test explicit hypotheses of morphologicval diversification of eudicots.