Strategies of flowering in dioecious plants in tropical coastal vegetation, Brazil

Abstract

Dioecious species are dependent on pollen vectors for sexual reproductive success. Male and female plants can express different blooming strategies, which respectively favour pollen donation and reception. This study characterised the flowering phenology of ten dioecious species, with different floral resources and pollination systems. The study focused on an area of sandy coastal plain in southeastern Brazil. We evaluated flowering events of male and female plants, in addition to the distribution of species flowering periods over 2 years. Regardless of the dependence upon biotic pollinators, all species shared the following traits: a single or a more expressive flowering event per year, with a duration ranging from intermediate to long, a high percentage of activity and intensity and high synchronism rates for intra- and inter-sexual morphs. In most species, males flowered first and more intensely following a sex allocation perspective. The flowering periods of dioecious species were randomly distributed throughout the year, preventing the identification of phenological drivers. The results suggest that the biotic (floral resources, pollen vector), abiotic (temperature, precipitation, day length) and phylogenetic factors do not seem to explain the observed flowering strategies. Since the restinga is a geologically recent tropical environment, the phenological attributes of the dioecious species possibly reflect the individual patterns of colonising species more than it does the interactions among them and with the environment.