The Polemoniaceae subfamily Cobaeoideae is comprised of four genera, Acanthogilia (1 sp.), Bonplandia (1 sp.), Cobaea (18 spp.), and Cantua (including Huthia; ca. 11 spp.). These genera exhibit remarkable diversification in vegetative, floral, and pollen morphology, as well as in life history traits and pollination systems. The relationships among Bonplandia, Cantua, and Cobaea are well understood; together they form a monophyletic group, and Bonplandia is the sister taxon of Cobaea. The phylogenetic position of Acanthogilia remains a topic of research. Combined studies of nuclear (ITS) and chloroplast (trnL-F and trnT-L spacers, and ndhF coding region) DNA provide a well-resolved, and generally well-supported, phylogeny of most of the species in this lineage. The phylogenies based on nuclear and chloroplast DNA sequence data are largely congruent, and they are consistent with preliminary phylogenetic analyses of morphological data. Comparative analysis of character evolution show that major changes in habit, vegetative morphology, and pollen morphology tend to be associated with long branches on the molecular phylogeny. In contrast, major changes in floral morphology and pollination system are less likely to be associated with long branches. In fact, floral characters and pollination systems often differ among closely related species. Floral characters tend to exhibit higher levels of homoplasy, and on average, there are more character states per character for floral characters, when compared to non-floral characters. These patterns suggests that in the subfamily Cobaeoideae, floral morphology, and perhaps pollination systems, are evolutionarily labile relative to non-floral characters.

Key words: evolutionary lability, floral mophology, homoplasy, molecular phyologenetics, morphological evolution, Polemoniaceae