Why are mimosa shy?

Mimosa has an enlarged organ at the base of petiole, which is called "leaf pillow". There are many parenchyma cells in the occipital lobe. These cells are very sensitive to external stimuli. Once it touches the leaf, the stimulus will be immediately transmitted to the leaf pillow, and the cell fluid of parenchyma cells will start to flow directionally, which will lead to the decrease of intercellular pressure at the lower part of the leaf pillow, and the phenomenon of leaf closure and petiole drooping will occur. 1 ~ 2 minutes later, the cell fluid gradually flows back to the leaf pillow, and the curled leaves will spread out again. Mimosa also got its name.