Variation in the gynoecia of Saxifragaceae provides an excellent system to explore the implications of developmental change in the generation of floral diversity within a phylogenetic framework. The traditional view has been that ovary position evolves from superior to inferior. Saxifragaceae are of interest because the complete range of ovary positions, from superior to inferior, has been reported not only across the family, but within individual genera. Most angiosperms with superior ovaries have an hypogynous floral ground plan and, hence, have ovaries that are "truly superior." In contrast, most inferior ovaries arise from an appendicular epigynous ground plan. Using a phylogenetic hypothesis based on 6-genes, we found that the evolution of ovary position in the family is complex, with evolution to greater inferiority occurring in some taxa, whereas in other instances there is evolution toward increasing superiority. Significantly, we found that members of Saxifragaceae reported to have superior ovaries actually possess an appendicular epigynous ground plan. Hence, these taxa do not have truly superior ovaries; rather, they represent "superior mimics." Furthermore, all gynoecia in Saxifragaceae are technically inferior. Our data also indicate that differences in ovary position at anthesis are a result of allometric shifts in the growth proportions of the superior vs. inferior regions of the ovary. These results have broad implications, potentially providing insights into gynoecial diversification throughout the angiosperms.

Key words: floral ontogeny, gynoecial diversification, Saxifragaceae