The use of biomechanics for the analysis of the form-function relationship in palaeobotany is reviewed. Four fields of application of biomechanics are discussed and illustrated, i.e. the functional analysis of plants and plant organs (examples: lianas, leaf margin types), reconstruction of fossil plants (growth habit, tree height), functional analysis of ontogeny (lianas, trees), and evolutionary pathways (evolution of early land plants). The biomechanical analysis of ontogeny and evolution is of particular interest because it not only reveals the biomechanical constraints and functional background of these processes, but also yields information concerning the underlying mechanisms. Ontogenetic and phylogenetic changes may resemble a self-organization process constrained by laws of biomechanics.