Flower biology and breeding system of Salvia sclareoides Brot. (Lamiaceae)

摘要

A remarkable diversity of floral adaptations and reproductive strategies has evolved in flowering plants as a result of natural selection mediated by pollinators. The form and functioning of sexual units determine the patterns of pollen dispersal and receipt and, together with post-pollination mechanisms including incompatibility systems, determine the plant reproductive fitness. Reproductive biology assumes a special importance in rare and endemic species due to restricted population/distribution sizes. Salvia sclareoides Brot. (Lamiaceae) is an endemic species of Iberian Peninsula with conservation interest for which little information is available. The aim of this work was to study the flower biology and breeding system of S. sclareoides and assess how reproductive traits, pollination services and herbivory affected the reproductive success of this species. One natural population was selected to study flower lifespan, floral rewards and sexual functioning and to determine the reproductive system; additionally, in three natural populations, pollen limitation and herbivory of sexual structures were quantified. Salvia sclareoides presents short-lived, nectar rewarding flowers arranged in inflorescences with several flowers simultaneously open. The flowers are protandrous, although the peak of pollen germinability and stigmatic receptivity coincided. Pollination experiments revealed that S. sclareoides is self-compatible, having some ability of spontaneous selfing. Still, the presence of pollinators significantly increased the reproductive success. Also, both quantitative and qualitative pollen limitation was observed. Finally, it was revealed that the reproductive success was also affected by herbivores that damaged significantly the sexual structures. The consequences of the obtained results for the dynamics of S. sclareoides populations are discussed.