The family Violaceae consists of 23 genera and 825-900 species worldwide. The nearly cosmopolitan genus Viola, by far the largest in the family, belies the family's otherwise almost strictly tropical distribution. The second and third largest genera, Rinorea and Hybanthus respectively, are pantropical (except Hybanthus concolor of eastern North-America) whereas the remainder are restricted to particular continental regions or island archipelagoes; the greatest generic diversity lies in Latin America. Current molecular phylogenetic studies of DNA sequence data from the trnL-F and rbcL chloroplast regions for genera and the Internal Transcribed Spacer nuclear ribosomal region for Viola groups worldwide have greatly elucidated both evolutionary relationships and biogeographic patterns at higher and lower levels. Chloroplast sequence data and mapping of biogeographic regions onto strict consensus trees for representatives across the family suggest a South American origin for the Violaceae, followed by radiation and dispersal from that continent. In addition, Hybanthus is splintered into 5 separate New World lineages and 2 Old World ones, each biogeographically coherent and supported by distinct combinations of morphological synapomorphies and base chromosome numbers. Aside from the New-to-Old World Rinorea radiation, key trans-Pacific dispersal events are represented by an Australian/South Pacific Hybanthus lineage descended from Central American Orthion ancestors, and lianescent New Guinean/South Pacific Agatea derived from a lianescent Latin American lineage composed of Anchietea and Corynostylis. An early trans-Atlantic long-distance event is suggested by Viola bicolor, the only native North American pansy and the basal-most member of Section Melanium, an otherwise European and western Asian lineage. The endemic Hawaiian species of Viola are now well established as derivatives from ancestral propagules of the Arctic tundra bog violet, Viola langsdorffii. Relative ages of these and shorter-distance regional events, based on levels of sequence divergence, range from the last glacial epoch, to the Eocene or earlier.

Key words: biogeography, dispersal, molecular phylogenetics, trans-oceanic disjunctions, Violaceae