Although poorly known and often neglected life forms, lianas and hemiepiphytes are frequently found in tropical canopies. Lianas (such as rattans) and hemiepiphytes (such as Ficus) are specialized life forms of the canopy that share a number of similarities, including spatial conditions and the requirement of a host plant. To better understand the biology of lianas and hemiepiphytes, the authors, during a 15-year period (1985-2000), collected data to compare several aspects of these two groups: geographic and taxonomic repartition, seedling and establishment phases, architectural development, and vegetative propagation. Considering the prevalence of lianas and hemiepiphytes in tropical canopies, the authors discuss the response of these plants to environmental conditions and speculate on their role in forest dynamics.