Breeding system and the role of floral visitors in seed production of a ‘few-flowered’ perennial herb, Paeonia broteroi Boiss. & Reut. (Paeoniaceae)

The breeding system and pollination ecology of Paeonia broteroi (Paeoniaceae), a selfcompatible, perennial herb, which produces few flowers (1-8) per season, are described in wo populations in mountains of southern Spain. Experimentally self-pollinated flowers yielded a significantly lower seed set (6-18%) than cross-pollinated flowers (23-29%), but the latter did not differ in seed set from open-pollinated flowers (30-31%). Seeds obtained from self-pollinated flowers were significantly lighter then seeds obtained from openand cross-pollinated flowers. Pollen and resource limitation, inbreeding depression and allocation to sexual functions are discussed to explain seed set. The role of different floral visitors (including bees, beetles and ants) on reproductive success was examined through exclusion experiments and efficiency tests. Only one species of bee (Andrena assimilis, Andrenidae) from the 25 insect species that were recorded during two study seasons seemed to be responsible for successful pollination. Thus, although flower morphology is open and excludes few if any floral visitors, most of the visitors were not suitable pollinators.