| Dilleniaceae are a pantropical family of angiosperms containing c. 400 species in 11 genera. They are renowned for their spectacular structural diversity, and are one of the few families to display variation across structural characters classically considered fundamental to understanding angiosperm evolution as a whole. Chapter One provides a brief overview of Dilleniaceae and their largest genus, Hibbertia, and summarizes the major findings of this dissertation in a language understandable by an educated layperson. Chapter Two is a molecular phylogenetic investigation of Dilleniaceae, utilizing Maximum Parsimony and Bayesian methods of phylogenetic inference on sequences of rbcL, infA, rps4, and the rpl16 intron regions of cpDNA for 56 ingroup taxa and 4 outgroup taxa. Dilleniaceae is resolved as a well-supported monophyletic group, with the pantropical genus Tetracera sister to the remaining Dilleniaceae. Within the clade of Dilleniaceae exclusive of Tetracera, the New World endemic genera are resolved into a well-supported clade sister to an Old World clade containing a clade of Dillenia and allied Indomalesian genera and a clade containing Hibbertia that includes the satellite genera Adrastaea and Pachynema. Many of the evolutionary trends, such as those concerning wood structure, pollen morphology, and floral morphology, that were influential in shaping previous views on Dilleniaceae evolution are discussed. Findings here suggest that many classically "primitive" character states for the aforementioned trends are derived in the context of the phylogeny. Chapter Three presents a revision of the genera of Dilleniaceae in an explicitly phylogenetic context. A thorough review of the structural features of the family, based on literature synthesis and numerous original observations from field work and herbarium studies, is presented. Character information is conveyed in a hierarchical context, reflecting the phylogeny. Chapter Four is a molecular phylogenetic and morphological study of Hibbertia. A molecular phylogeny of Hibbertia, based on Maximum Parsimony and Bayesian analyses of ITS nrDNA and rpl16 intron cpDNA sequence data for 118 taxa shows the genus to be resolved into four well-supported clades. The New Caledonian taxa form a monophyletic group. The floral ontogeny of H. conspicua is examined. The inflorescence of H. polystachya is analyzed. Monosymmetric flowers in Hibbertia have their plane of symmetry in the transverse, not median, plane of the flower. |
