PHYLOGENY AND FLORAL DIVERSITY IN THE GENUS GARCINIA (CLUSIACEAE) AND RELATIVES

The pantropical genus Garcinia comprises more than 250 species of dioecious trees and shrubs that are a common component of lowland tropical forests. The genus exhibits as extreme a diversity of floral form as is found anywhere in angiosperms, and there are many unresolved taxonomic issues surrounding it. To evaluate morphology-based classification schemes involving Garcinia and its relatives and to examine floral diversity in the genus within a phylogenetic context, higher-level relationships among a broad sample of Garcinia and close relatives were inferred by conducting Bayesian, parsimony, and likelihood analyses of 70 species with sequence data from two nuclear genes, granule-bound starch synthase (GBSSI) and the internal transcribed spacer (ITS). These results support a broad circumscription of Garcinia and the monophyly of tribe Garcinieae. Within Garcinia, several clades are supported that share particular combinations of floral characters and generally correspond to sections recognized in the most recent treatment of the genus. The phylogenies suggest that all species of Garcinia fall into two major lineages, one characterized by the presence of nectariferous floral organs of uncertain derivation, such as central disks, antesepalous lobes, and intrastaminal ring-shaped disks, and the other by their absence.