Re: Why does the toch-me-not plant shrink back when we touch it?

Some how this plant changes the water pressure (turger) at the base of 
the leaf, which moves the plant parts. Several plants respond to touch or 
motion this way. Members of the Mimosa plant family and some members of 
the impatients plant family express this response to touch. To answer 
your question, it moves or shinks back because of a pressure change at 
the leaf base.