Like humans and other animals, plants do not have a well-defined nervous system but they can sense things in their surroundings in the presence of various stimuli like light, gravity, water, touch etc. and respond them by different hormonal actions. The plants coordinate their behavior against environmental behavior by these hormones. This process is called coordination. These hormones are organic chemicals and play a vital role in different plant parts that results the movement of plant part in response to a stimulus. In animals, the control and coordination takes place in coordination of both nervous system and hormones.