The Dilleniaceae are an angiosperm family consisting of 10-14 genera and c. 350 described species with a pantropical distribution, extending into temperate Australia. Within current conceptions of angiosperm phylogeny based on analyses of sequence data, the Dilleniaceae are eudicots with rather uncertain affinities, though they are weakly supported as sister to the Caryophyllales in studies utilizing three genes (Soltis et al., 2000; Hoot et al., 1999). This study addresses the infrafamilial relationships of the Dilleniaceae using nucleotide sequence data from the plastid loci rbcL, ndhF, rps4, and infA, in addition to a morphological data set. Maximum parsimony analysis of preliminary data places Tetracera, the only pantropical genus in the family, as sister to the remainder of the family. Within the rest of the family, the New World endemic genera form a clade that is sister to a clade of the Old World endemic genera. The Old World clade is comprised of two subclades: 1) a clade containing Acrotrema, Didesmandra, Dillenia, Schumacheria , and 2) a clade containing Hibbertia and allied segregate genera. The (segregate) genera Adrastaea and Pachynema are clearly embedded within Hibbertia as it is currently conceptualized. Floral morphological features that have traditionally been viewed as primitive, such as exceptionally large numbers of stamens (200+) and numerous carpels (more than 10), are clearly derived within the family, and additionally are features of uncommon occurrence within the family as a whole. Androecial zygomorphy has at least two independent derivations within the family, once in clade containing Schumacheria and Didesmandra, and at least once within Hibbertia. These and other morphological features, along with biogeographic implications, will be discussed in the context of the phylogenies presented.

Key words: biogeography, Dilleniaceae, floral morphology