Subdioecy, which includes females, males, and hermaphrodites in a population, is a rare sexual expression in angiosperms. Although there have been several hypotheses about the reasons why subdioecious plant species exist, field studies examining the differences in reproductive successes through female/male functions among hermaphrodites, females and males are limited. We found that the female reproductive success of females was significantly higher than hermaphrodites in a subdioecious plant Eurya japonica. As for male reproductive success, it is necessary to clarify the pollen germination rate, pollen tube growth, fruit and seed production, seed germination rate, and seedling establishment rate using pollen of males and hermaphrodites. So, in this study, the hand-pollinated reproductive successes were compared using the single-individual's pollen (single pollen) and multi-individual's pollen (mixed pollen)from hermaphrodites and males in E. japonica.

The fruit sets using mixed pollen were significantly higher than those using single pollen. Furthermore, both in single- and mixed- pollinations, male individuals sired many more fruits than hermaphrodites. In addition to these results, we will report the results of seed production and seed weights, and then discuss the causal factors of maintenance of subdioecy in E. japonica.