Abstract: Heterostyly is a distinct floral polymorphismand herkogamy pattern and includes distyly and tristyly. Heterostyly has been reported in 31 families of angiosperms. It is considered to play an important role in protecting the functional pistil and stamens, ensuring reproduction by avoid selfing, and increasing male fitness and outcrossing rates by reducing s exual interference between female and male function. Here, we review recent advances in heterostyly research, with emphases on (1) types, floral syndrome, ancillary polymorphism and population structure of heterostylous species; (2) taxonomy, origin and evolution of angiosperms that exhibit heterostyly; and (3) the evolutionary significance of heterostyly . We also discuss prospects for further research. Our review provides a database for further study of the evolutionary biology of heterostylous species and points to the significance of heterostyly in the evolution of breeding systems of plants.

Key words: angiosperm, breeding system, evolution, flower polymorphism, heterostyly