Potential for mixed mating in the protandrous perennial Saponaria officinalis (Caryophyllaceae)

The prevalence of mixed mating among plant species is intriguing from an evolutionary perspective because most theoretical models predict that plant species should evolve towards either complete selfing or complete outcrossing. Several ecological factors, such as pollinator variability, have been invoked to explain this discrepancy. However, empirical data detailing the mechanisms of selfing and the impact of selfing on progeny fitness are rare. One trait that might allow a high degree of variability in outcrossing rates is dichogamy, the temporal separation of male and female functions within perfect flowers. The present study examines the potential for mixed mating by using floral manipulations in five populations of Saponaria officinalis, a protandrous perennial herb. Bagged flowers produced fewer seeds than control flowers and open‐pollinated emasculated flowers, and the emasculated flowers were not significantly different from the controls. Controlled pollinations indicated that there were no differences between seed production in geitonogomous, outcrossed or control groups. There were some differences in seed weight between the pollination treatments, but there was no effect of pollen source on germination date or seedling weight. These results suggest that insect visitation provides an important contribution to seed set, even though self‐pollination is capable of producing viable seeds.