Why Do Leaves Of Mimosa Plant Close On Touching?

 

As a kid, the peculiar behaviour of this certain plant must have fascinated all of us atleast once. Everyone of us has experienced the phenomenon of mimosa leaves closing on their own, as soon as we touch them. But when we grew up our curious mind started asking the question "why?" Well, here's your answer!

This behaviour displayed by the mimosa plants is known as "Thignomasty". Thignomasty occurs as a result of changes in pressure within a special kind of cells called "Pulvinus". The pulvinus is located at the base of each leaflet and contains the motor cells which control the movement of the leaves. 

When we touch the leaves, the motor cells get triggered and start releasing potassium ions, which in turn stimulates the change in turgor pressure. As a result, the leaves fold inward, causing a characteristic leaf-closing response.