WHY DOES THE TOUCH-ME-NOT PLANT SHRINK WHEN TOUCHED?

The touch-me-not plant shrinks within a few minutes of being touched. This is due to the loss of turgidity by cells within the pulvini-specialised motor organs at leaf joints. Upon stimulation the leaf cells lose potassium ions which causes water to leave the cells by osmosis. It takes about 10 minutes for the cells to regain turgidity and the leaflets to open out.