Wind-Pollination in the Understorey of a Rain Forest in Costa Rica

Abstract

SUMMARY (1) In Trophis involucrata, a dioecious tree in the understorey of a Lowland Tropical Rain forest in Costa Rica, the anther filaments are held under tension, and as the flower opens the filaments spring out violently and the anthers concurrently release pollen in a small cloud. The pistillate flowers are green and inconspicuous, and lack not only perianth but also nectar, and are thus devoid of attractants and rewards for pollinators. (2) In addition to these morphological features, a number of other observations and experiments suggest that Trophis involucrata is wind-pollinated. (3) Analysis of the dispersion pattern of plants indicates that the average distance between staminate and pistillate plants is small (6-6 ? 3.3 m), and that the two sexes are randomly distributed with respect to each other. It is suggested that both factors should facilitate the capture of pollen by pistillate plants. (4) Other examples of wind-pollination in lowland tropical humid forests are described, and the factors responsible for the evolution of anemophily in such forests are discussed.