define

 The leaves of Mimosa pudica plant close up under the inflence of various stimuli, such as touching, warming, blowing, or shaking. The stimulus can also be transmitted to neighbouring leaves. These types of movements have been termed seismonastic movements. The movement is caused when the leaves lose turgor pressure.

The seismonastic movement is caused by rapid shrinkage of motor cells of the main pulvinus in which dynamic changes in actin cytoskeleton occur. Before the movement, long and thick actin filaments are observed throughout the cytoplasm, whereas after the movement, only short and thin filaments are observed.