WHY ARE THERE SO MANY AND SO FEW WHITE FLOWERS

Though the world we see appears to be rich in white flowers, this is n ot the case for animals, such as insects, with ultraviolet (UV) recept ors. In fact, flowers that appear white to insects ape very rare. we a nalyse this phenomenon to highlight new discoveries in the mechanisms of insect vision that may have influenced the evolution of flower colo ur. Our analysis reveals that an understanding of biological signallin g requires a comprehensive understanding of sensory physiology and per ceptual psychology. An evaluation of UV signals alone may not be helpf ul, as this can be as inaccurate as models based solely on the human v isual system. We interpret floral colours and their frequency in natur e from the more relevant perspective of insect colour vision.