The relationship of anatomy to morphology in plants: a new theoretical perspective

Some guiding principles are given in five theses to provide a synthesis between comparative morphology, the science of the outer form (Gestalt) of plants, and plant anatomy as the science of the histological structure of plants. A short historical review shows that both are concerned with different organismal units. In morphology the whole plant is the unit; in anatomy it is the cell. The differentiation of the plant form has little to do with the cellular structure, which is secondary, because the cell walls are used as a means of form stabilization. But the existence of the cell wall system gives the plant the option to differentiate the resulting tissues and the cells the option to be latent organisms. The cormophytean organization of the land plants started with an open, flat thallus presenting surfaces to the environment. In megaphyllous cormophytes the leaf is the main plant organ, which has taken over the essential plant functions into a closed, modifiable, developmental program. Stem and root organs are added during evolution, staying in an open condition and growing monotonously.