The power of movement in plants: the role of osmotic machines

Abstract

The apparent and often spectacular movements of animals and insects, movements of the whole organism in relation to its surroundings arising from internally generated forces, have always been, by their very ubiquity, uppermost in our perception of motion in the living world. Movement in plants, generally of one organ in relation to the whole plant, whilst sometimes spectacular, have often in the past been seen as rather esoteric events, amusing perhaps, but of little importance in the general biological scheme of things. However, this is not so; plant movements are quite widespread in occurrence and all are most probably manifestations of a single physiological process, the change in volume of special motor cells. One particular movement, the opening and closing of stomata, which provides a basic control of photosynthesis, is of fundamental importance to the existence of the whole biosphere.