The New Student's Reference Work/Movements
Move′ments (in plants). Movement from place to place is possible only to the simpler plants and those living in water or on wet surfaces. To accomplish it, the protoplasm is either extended into one or more slender threads, called cilia, which bend quickly and act somewhat as oars; or into broad, blunt protrusions by means of which the cells creep. (The method of some movements is still unknown.) Movements of larger plants are due to bending. This may be done by unequal growth on different sides or by unequal turgor (which see) on the opposite sides. Motor organs (which see) are regions of the leafstalk specially arranged to permit curvature by the latter method. Movements are usually executed in response to some stimulus, though some seem to be spontaneous. See Irritability, Chemotaxis, Chemotropism, Geotropism, Heliotropism, Hydrotropism, Phototaxis, Rheotropism and Thermotropism.