Evolution of land plant architecture: beyond the telome theory

Abstract For well over 50 years, the telome theory of Walter Zimmermann has been extremely influential in interpreting the evolutionary history of land plant architecture. Using the “telome/ mesome” distinction, and the concept of universal “elementary processes” underlying the change in form in all plants, the theory was an ambitious synthesis based on the proposition that evolutionary change might be understood by a simple set of developmental or evolutionary rules. However, a major problem resides in deciding exactly how assertions of change are to span both developmental and evolutionary domains simultaneously, and, we argue, the theory critically fails testability as a scientific theory. Thus, despite continued popularity for the descriptive terms derived from the theory in evolutionary studies of early land plants, time has come to replace it with a more explicit, testable approach. Presented here is an attempt to clarify perhaps the most important issue raised by the telome theory—whether simple ch...