Abstract

Trap pollination is a relatively rare pollination system despite occurring in several distantly related angiosperm groups. Trap pollination occurs in at least three angiosperm groups, the Piperales, the Asterids and the Monocots. These groups diverged very early in the adaptive radiation of the angiosperms and traps vary greatly in their structure across groups. This suggests that trap pollination has evolved independently several times and so ontogenetic constraint is unlikely to be a major reason for their rarity across the angiosperms. This paper tests the hypothesis that an important limitation of trap pollination is that it produces sexual conflict between male and female floral function and that this may contribute to its rarity as a pollination system. It presents results examining the benefits and costs of trap pollination in one genus, Arum (Araceae, Monocots) and evaluates the extent to which conclusions may apply more widely across the angiosperms.