Floral colour changes as cues for pollinators

Abstract

PLANTS have evolved traits that enable them to influence directly the behaviour and movement of their pollinators. Here I show that flowers in at least 74 diverse angiosperm families undergo dramatic, often localized, colour changes which direct the movements of a variety of pollinators to the benefit of both participants. Floral colour change was first noted almost 200 years ago¹ and is known in a variety of species^2–17, but the prevalence and significance of the phenomenon have gone largely unrecognized. I find that retention of older flowers increases a plant's attractiveness to pollinators from a distance, that pollinators discriminate between floral colour phases at close range, and that the discrimination involves learning. The phenomenon of floral colour change is taxonomically widespread, morphologically variable (Fig. 1), and physiologically diverse. It has evolved independently in the angiosperms many times and provides a striking example of functional convergence.