Abstract: Gynomonoecy is the sexual system in which individual plants have both female and hermaphrodite flowers. Compared to the other sexual systems, the adaptation and diversification of this system have been largely underappreciated. Gynomonoecious species have a diversity of floral traits and pollination systems despite that they account for only about 3% of the total species. Several hypotheses assume that the adaptive advantages of maintenance of gynomonoecy may enhance outcrossing, avoid pollen-pistil interference, permit flexible resource allocation of paternal and maternal functions, defense herbivores and increase the attractiveness to pollinators. However, the studied species were mainly restricted to the Asteraceae and a few empirical studies available rarely supported these hypotheses. Further studies are needed regarding the reproductive biology of gynomonoecious species in different groups and on different pollination systems. Such studies, together with phylogenetic studies on the groups concerned, will help us have a better understanding of the origin and evolution of gynomonoecy.

Key words: Gynomonoecy, sexual systems, adaptive advantages, reproductive biology.