Attracting pollinators and achieving successful reproduction is essential to flowering plant species, which evolved different strategies to cope with unpredictable pollination service.The ability of selfing is most widespread and represents a reproductive insurance under varying conditions.In this study, we investigated reproductive success in Centaurea cyanus, a self-incompatible declining Asteraceae species.We measured Book seed set under outcrossing and autonomous selfing and assessed the impact of capitulum structure (i.e.
, the number of disc florets) on reproductive success.We report that the incompatibility system is either flexible or evolving a breakdown in this species, since autonomous selfing often resulted in production of few seeds.We also show that capitulum structure has a strong impact on reproduction, with smaller inflorescences presenting a better ability to self than larger ones, while larger Grass Strimmer Blade inflorescences performed better than smaller ones when cross-pollinated.Variable capitulum structure in this Asteraceae species may therefore represent a reproductive strategy to achieve efficient reproduction under diverse pollination environments.Our results also suggest that this declining species might be disrupting its auto-incompatibility system in response to reduced habitats and declining population sizes.