In this dissertation, the Caryophyllales sensu lato are explored and developed as a system for studying the evolutionary development of the angiosperm perianth. The phylogenetic context of the Caryophyllales is defined with a molecular phylogenetic analysis employing eight plastid genes, two nuclear genes and the entire plastid Inverted Repeat for forty taxa representing the major families within the Caryophyllales sensu lato. Stochastic character mapping and parsimony reconstruction analyses reveal a minimum of nine independent origins of the differentiated perianth within the core Caryophyllales clade. Molluginaceae are revealed to be polyphyletic such that two genera, Hypertelis and Macarthuria , form disparate lineages with respect to Molluginaceae sensu stricto. The implications of this resolved polyphyly for our understanding of the evolution of pigmentation within the core Caryophyllales was explored by stochastic character mapping and parsimony reconstruction analyses. Multiple origins of betalains are suggested, with reversals to anthocyanins. The value of Multiple Displacement Amplification is demonstrated as a means to augment rare archival DNA stocks for molecular phylogenetic analysis. The evolution of various lineages of MADS-box transcription factors was explored in relation to the novel evolution of petaloid staminodes within the plant family Aizoaceae. Fifty-four new MADS-box gene loci were sequenced from six species of Caryophyllales. Phylogenetic analyses of these loci demonstrate an absence of gene duplication, therefore, increases in MADS-box gene complement do not play a role in the evolution of the novel petaloid staminodes in Aizoaceae. Finally the evidence for a shared genetic pathway for petal development was assessed by examining the morphological structure and genetic processes in two distinct petaloid organs in Aizoaceae, the petaloid staminodes and petaloid tepals. It is determined that at multiple levels the petaloid staminodes and petaloid tepals are not-homologous. There is no morphological or genetic evidence to recommend the concept of a conserved petal identity program in Aizoaceae. The petaloid organs in Aizoaceae should therefore be regarded as convergent evolutionary events that have occurred independently of a hypothesized petal identity program. Thus, the concept of a conserved petal identity program across all core eudicot angiosperms is refuted.