Format: ORAL

Steven D. Johnson

Centre for Functional Biodiversity, University of KwaZulu-Natal

Plant species that are polymorphic for style length or orientation have evolved repeatedly in the angiosperms. Stylar polymorphisms are considered to promote efficient cross-pollination, but have rarely been considered in terms of floral adaptation to particular pollinators. Here I explore how polymorphisms involving length and orientation of styles (and also stamens) interact with pollinators to influence the fates of pollen. I compare the effectiveness of different flower visitors as pollinators of long-tubed distylous plants and consider the conditions under which stylar polymorphisms could be maintained through disassortative pollination. I also consider whether selection for traits that enable transfer of pollen on the wings of insects can explain the evolution of enantiostyly in some plant lineages. The evidence reviewed shows how stylar polymorphisms generally promote efficient pollen transfer via morphological fit with specific body parts of various animal pollinators.