Sex among the flowers: The distribution of plant mating systems

Previous reviews of plant outcrossing rate survey data have agreed that pre dominant selfing and predominant outcrossing are alternative stable states of mating system evolution. We reanalyzed the most recent data and plot out crossing rates as a continuous variable rather than as a class variable. Wi nd-pollinated species are indeed bimodal. However, the shape of the distrib utions for animal-pollinated species reveals that intermediate rates of out crossing are common (49% of species fall between 20% and 80% outcrossing). Consequently, we suggest that mating system is best considered a continuous rather than a discrete character of plant populations.