Blom, C.W.P.M., Bögemann, G.M., Laan, P., van der Sman, A.J.M., van Flooding frequencies and intensities determine both species composition and the behaviour of in dividual plants along many rivers in the world. In this context, this paper describes the vegetation zonation associated with the fluctuating water levels of the river Rhine in the eastern part of The Netherlands. To obtain insight into the morphological and physiological processes of plants that have been shown to possess contrasting tolerances to Hooding, certain species were chosen as being repre sentative of the vegetation types from the river foreland and subsequently used in experimental stud ies. These species, of the genera Rume.x and Chenopodium, were subjected to various flooding regimes