| The traditionally circumscribed Capparaceae have been considered a ‘trash-basket’ family, their monophyly suspected, and are in need of detailed phylogenetic study. The family also presents an incredible diversity of floral variation including changes in floral symmetry, loss of perianth whorls, a wide range of stamen number, and a pronounced intercalary elongation zones that may produce gynophores. In this thesis, I summarize molecular systematic work on traditional Capparaceae and relatives with emphasis on floral evolution and biogeography of this intriguing group of plants.; Phylogenetic analyses based on chloroplast sequence data of a broad sampling across the traditional circumscription of Capparaceae and closely related Brassicaceae provide insight into relationships. These analyses suggest the recognition of three major clades: Brassicaceae, Capparaceae subfamily Capparoideae (excluding genus Forchhammeria), and Capparaceae subfamily Cleomoideae (including two small subfamilies, Dipterygioideae and Podandrogynoideae). The monophyly of Capparaceae is strongly contradicted with subfamily Cleomoideae most closely related to Brassicaceae. Based on these analyses I advocate the recognition of three separate families: Capparaceae (largely equivalent to subfamily Capparoideae), Cleomaceae (largely equivalent to subfamily Cleomoideae) and Brassicaceae. Anomalous Forchhammeria as well as Tirania of traditional Capparaceae are most closely related to other families of the order: Gyrostemonaceae and Resedaceae.; Patterns of floral morphology, breeding systems, and geographical distributions established by phylogenetic studies were assessed. Habit and fruit characteristics demarcate Capparaceae from Brassicaceae plus Cleomaceae, whereas floral symmetry, stamen number, fruit type, and leaf type all show homoplasy. Among Capparaceae, Cleomaceae, Brassicaceae and related taxa (Gyrostemonaceae, Resedaceae, Tovariaceae, Pentadiplandraceae, Emblingiaceae, Forchhammeria and Tirania) patterns of morphological evolution are complex with respect to number of organs in flowers as well as breeding systems. Comparative floral developmental studies within Cleomaceae reveal there is variation in early floral development despite similarities mature flower ground plans. Molecular clock analyses indicate that all these taxa are relatively young and diverged less than 70 million years ago. |
