The present study will help answer questions of tree type evolution, function, optimum, and tree construction types, using the approach of constructional morphology which to date has been widely neglected in palaeobotany and botany. First, the evolution pattern of the earliest Devonian trees is analyzed and explained, including a brief introduction of tree biomechanics. Then fossil and recent trees are studied from the viewpoint of constructional morphology with the main emphasis on the trunk as the most characteristic element of a tree. The various trunk constructions are classified into...