Low fruit set in the abundant dioecious tree Clusia hilariana (Clusiaceae) in a Brazilian restinga

Clusia hilariana (Clusiaceae), a dioecious tree, is an important nurse plant in the open, patchy restinga vegetation of coastal sandy plains in northern Rio de Janeiro (SE-Brazil). Although highly abundant locally, we found low production of fruit and viable seeds in open-pollinated as compared to hand-pollinated flowers. Reward from flowers of both sexes was resin, which was produced in higher quantities in male flowers. Flower visitors, including honeybees, were infrequent. We argue that low sexual reproductive success was due to inefficient pollen transport, and that vegetative propagation may contribute significantly to the high abundance of plants of this species.