Are unisexual flowers an appropriate model to study plant sex determination?

Abstract

Unisexual flowers are used as a model for studying plant sex determination, but it is a general phenomenon that they result from the developmental inhibition of one type of reproductive organ, which prevents sex cell formation. This should not be categorized as sex differentiation, but rather as the promotion of outcrossing. An alternative view is to regard 'sex' as division of types of gametes, which occurs only in eukaryotes, while regarding 'sex differentiation' as mechanisms that occur in the soma to ensure heterogametogenesis, which occurs only in multicellular eukaryotes. In the light of these new definitions, distinguishing real- and pseudo-sex differentiation is an interesting issue in plants.