The colour patterns of angiosperm flowers visited by bees and hoverflies were shown to provide a dual signalling system, giving the flower-visitors visual orientation cues for the initial detection of flowers, as well as for learned discrimination. Pollinators show an innate response to interspecifically uniform colour signals, which enable them to detect flowers and to orient towards the site of reward. Interspecifically diverse colour signals provide pollinators with cues for learned discrimination between flowers of different species.