XVI International Botanical Congess

Rubiaceous taxa have many sexual systems, floral morphologies and growth forms. We optimized evolutionary changes for these characters on a phylogeny proposed by Bremer et al. based on rbcL sequence data. Character states of 62 genera from three subfamilies of Rubiaceae were surveyed from 56 floras. Genera with multiple states were coded as polymorphic. Most evolutionary changes were within genera, implying repeated, independent evolution of heterostyly, dioecy, large flowers, and trees and herbs. Compared to a random distribution, Cinchonoideae had a significant excess of trees and Rubioideae had excess herbs and heterostylous taxa. Some genera (e.g. Gardenia, Mussaenda, Psychotria) are evolutionary hot-spots for all three characters. When characters at low taxonomic levels show high evolutionary vagility, convergence is implicated over phylogenetic constraint.