The Evolution of Empty Flowers

This paper describes a simple model intended as a first step towards a quantitative theory of the flower. It divides both flowers and their visitors into two categories: the flowers may either produce a substantial volume of nectar ("secretors") or none ("cheaters"), while the insects either attempt to discriminate between them and enter only secretors ("selectors") or enter any flower encountered ("neglectors"). If the insects can learn the state of the plant population and behave accordingly, then they should all either select or all neglect exclusively; the plants adopt a mixed strategy with each plant producing a similar proportion of cheating flowers. The proportion increases as the time required by the selectors to discriminate between cheaters and secretors increases relative to the time required to extract the nectar. The argument is of general interest because it represents a new theory of nectar concealment. Cheating is known to occur in some plants, but it is not known how widespread the strategy is.