Frequency of flower visitors and achene production increase with rising population size in the self-incompatible herb Centaurea scabiosa (Asteraceae)

Abstract Self-incompatible, non-clonal plant species are especially dependent on the activity of flower visitors for seed production. Therefore, populations these plants vulnerable to a reduced visitation rates, but also increased isolation by extinction local populations. To study how Centaurea scabiosa , self-incompatible, bee-pollinated herb changed over time in region Bonn, we collected historical population records area and investigated their current status. We found that more than half subpopulations mentioned literature between 1950 2012 (38 65) have since disappeared. Small were most vulnerable, whereas medium large size. In second step, studied frequencies achene production weight across 14 extant both frequency positively related Achene was neither nor These results clearly indicate pollen transfer lower pollination rates may contribute small . Overall our call an intensified monitoring self-incompatible species.