Book excerpt: This synthesis of the growing body of information from research on epiphytes and their relations with other tropical biota provides a comprehensive overview of basic functions, life history, evolution, and the place of epiphytes in complex tropical communities. Epiphytes comprise more than one-third of the tropical vascular flora in some tropical forests. Growing within tropical forest canopies, epiphytes are subject to severe environmental constraints, and their diverse adaptations make them a rich resource for studies of water balance, nutrition, reproduction and evolution.