Phylogenetic analysis using an expanded data set of nrDNA ITS and PHYC and cpDNA accD and trns sequence data retrieves a monophyletic 'Synostemon' F.Muell. ('Phyllanthaceae, Phyllantheae, Flueggineae'), previously subsumed into 'Sauropus' Blume or 'Phyllanthus L. Sauropus s. str.', excluding 'Synostemon', is shown to be nested within 'Breynia' J.R.Forst. & G.Forst. (Chapter 2). Morphological data clarifies infrageneric relationships within 'Sauropus' and its species are transferred to 'Breynia' in a new subgenus, 'B. subgenus Sauropus' (Blume) Welzen & Pruesapan (Chapter 3). 'Synostemon hamersleyensis' I.Telford & Naaykens, a recently discovered new species endemic to ironstone detrital formations of the Hamersley Range in the Pilbara, central Western Australia, is named, its distribution, habitat and contentious conservation status discussed (Chapter 4).

• Premise of the study: The broad austral distribution of Schoeneae is almost certainly a product of long-distance dispersal. Owing to the inadequacies of existing phylogenetic data and a lack of rigorous biogeographic analysis, relationships within the tribe remain poorly resolved and its pattern of radiation and dispersal uncertain. We employed an expanded sampling of taxa and markers and a rigorous analytic approach to address these limitations. We evaluated the roles of geography and ecology in stimulating the initial radiation of the group and its subsequent dispersal across the southern hemisphere. • Methods: A dated tree was reconstructed using reversible-jump Markov chain Monte Carlo (MCMC) with a polytomy prior and molecular dating, applied to data from two nuclear and three cpDNA regions. Ancestral areas and habitats were inferred using dispersal-extinction-cladogenesis models. • Key results: Schoeneae originated in Australia in the Paleocene. The existence of a "hard" polytomy at the base of the clade refl ects the rapid divergence of six principal lineages ca. 50 Ma, within Australia. From this ancestral area, Schoeneae have traversed the austral oceans with remarkable frequency, a total of 29 distinct dispersal events being reported here. Dispersal rates between landmasses are not explicable in terms of the geographical distances separating them. Transoceanic dispersal generally involved habitat stasis. • Conclusions: Although the role of dispersal in explaining global distribution patterns is now widely accepted, the apparent ease with which such dispersal may occur has perhaps been under-appreciated. In Schoeneae, transoceanic dispersal has been remarkably frequent, with ecological opportunity, rather than geography, being most important in dictating dispersal patterns.

Aim: Our aim was to implement a molecular dating analysis and assess divergence times among taxa of Winteraceae. This enabled us to test hypotheses of vicariance versus long-distance dispersal to explain intercontinental disjunctions in the family. Location: Madagascar, Australia (including Lord Howe Island), New Zealand, New Caledonia and South America. Methods: We sampled all Australian species and subspecies of Winteraceae. We also included the monotypic 'Takhtajania perrieri' and at least two species of each genus from New Zealand, New Caledonia and South America. Three sets of sequences were combined into one data matrix, including two internal transcribed spacer (ITS) data sets and a trnL-F data set. Both ITS data sets included all genera of Winteraceae, and the paralogous genes identified in 'Zygogynum' s.l. in a previous study were sequenced and aligned in separate ITS data sets. A Bayesian molecular phylogenetic tree of extant Winteraceae was used as a backbone constraint in PAUP to establish the placement of fossils. Bayesian analyses were performed using BEAST, implementing fossil priors to fit lognormal distributions, to test a maximum-parsimony phylogeny and assess divergence times. Results: Interspecific relationships generally agreed with previous analyses. In particular, 'Bubbia comptonii' was found to be sister to the rest of the 'Bubbia/Zygogynum' clade, but our analysis has uniquely found sister clades within this group: one from New Caledonia, and one from Australia including Lord Howe Island. The phylogeny yields an age of 91.2 Ma with a 95% confidence interval of 118-67 Ma for crown-group Winteraceae. Main conclusions: The estimated age of 'Takhtajania' is consistent with its origin in Madagascar as a result of Gondwanan vicariance - the only angiosperm for which this has been demonstrated with confidence. Differentiation of the rest of this ancient clade is a complicated story of vicariance as a result of the rifting, submergence and exhumation of continents and of long-distance dispersal and extinctions.