Reproductive ecology of Saxifraga florulenta, a monocarpic perennial paleo-endemic of the Alps

Abstract

Saxifraga florulenta is a monocarpic species endemic to SW Alps, whose reproductive biology is still unknown. Its knowledge may provide useful information on how the species may face the global warming. In this study, we investigated the plant–pollinator interactions and the mating system of the plant. We described the phenology of the inflorescences, we evaluated the type of pollinators, we verified self and cross-pollination and lastly we quantified the reproductive success of the plants. In spite of the low visitation rate of pollinators, S. florulenta shows high fruit set and seed set. The plant exhibits a prolonged flowering period and has a definite inflorescence, characterized by a sequential blooming bearing both female- or male-phase flowers at the same time; in addition, flowers show a delayed maturation and movement of stamens. These floral and inflorescence traits lead to a mixed reproduction mode which guarantees reproductive success by adopting the “best of two worlds” strategy. The species maximizes its resource investment by having inflorescence size and number of flowers directly related to plant size, whilst fruit and seed set as well as seeds per flower did not show any statistically significant relationship with plant size.