Hummingbird pollination ofMalvaviscus arboreusin Costa Rica

Abstract

Abstract Malvaviscus arboreus is a self-compatible shrub or small tree native to Costa Rica. Floral morphology, nectar flow pattern, and observations of visitor behaviour, all indicate that flowers are specialised for hummingbird pollination. The principal pollinator in Guanacaste Province during the dry season was the cinnamon hummingbird (Amazilia rutila); numerous other flower visitors removed nectar and pollen but only hummingbirds effected pollination. Anthers have dehisced and stigmas are receptive by dawn, and flowers function for a single day, although the corolla may persist for two days before abscission. Peak nectar production occurs in the early morning coinciding with highest visitation rates of pollinators. Pollen grains are large and linked by viscin threads which probably aid in pollen transport. About 50% of flowers set fruit; the fleshy fruit usually contain three or four seeds and are probably dispersed by birds. Dispersal of pollen and fruit by birds gives a large neighbourhood size co...