Inundation forests of várzeas cover large part of the Amazon area. In spite of their importance as fish breeding grounds, a detailed description of such forests in the Colombian Amazon has so far been lacking. This is a comprehensive study, concerning a structural and phyto-sociological classification and ordination of inundation forests, their environmental setting, palynological studies and a study of the potential economic significance of products from these forests. The results show that the environmental setting is very diverse. A mixture of soil and water types, variation in drainage and the seasonality of flooding cause this. All this leads to clearly defined forest types (7 structural and 16 phyto-sociological types). The potential economic significance of these forests varies greatly between the various forest types. In well-drained forests less than 50% of the individuals have a known use, while in poorly drained forest this is over 80%. The example of oil production from palms is also elaborated. Based on a palynological analysis of the temporal variation in the vegetation, the author stresses that management and conservation plans should acknowledge the dynamic nature of inundation forests and not treat them as fixed, unchangeable features of the landscape.