Why do leaves of a touch me not plant fold up when touched?

A touch me not plant has compound leaves with a slightly swollen structure at the base called pulvinus. The lower half of this is compound of thin walled cells with large inter-cellular spaces and the upper half are thick walled without any inter cellular spaces.

When the leaves of the plant are touched, the upper turgid cells put pressure on lower flaccid cells and the leaves fold up.

Funny Logic

• Because it knows that man has not touched anything without exploring it.