The effect of pollinators, predators, and energy constraints on the floral ecology and evolution of Trillium erectum.

The reproductive success and energy budgets of single and multiflowered plants of Trillium erectum L. (Liliaceae) were assessed over a period of 4 years. Plants with more than one flower were found to attract more pollinators, to be less vulnerble to predation by Tortricid moths, and to produce more seeds than single flowered plants. Despite the reproductive superiority exhibited by multiflowered plants, most plants (85%) in the population studied were single flowered. It is shown that even though the insect interactions make it advantageous to produce more than one flower, most plants lack the energy to do so. The optimality approach which has guided previous studies of this kind is criticzied.