Re: on touching why do the leaves of mimosa pudica close and how does it happen

Sensitive plant (Mimosa pudica) has a special swollen area at the base of each 
leaf and leaflet, termed the pulvinus. When the leaf is stimulated by touch or 
shaking, cells in the lower half of each pulvinus can rapidly pump potassium 
ions out. The water follows the ions due to osmosis and the cells shrink. This 
causes the leaf and leaflets to move rapidly. 

Within the last couple years, some researchers have suggested that fibrils in 
the cell cytoskelton may be involved but that is still being worked out.

References


Photos and Drawings of Mimosa pudica Pulvinus



Leaf Movements Mimosa pudica


Plants Have Feelings Too