The (mental?) reactions/responses of plants is detectable by lie detector. These can be telepathic (responding to thoughts) or from external stimuli (fire or rain). What we know about this subject is extremely limited but, let try to approach it from a different view.
With the knowledge of this phenomena, it is believed that the grasses and forests may have their own communication and social life. This communication is not in the form of language (words) indeed, most of human communication is not either! for lack of a better word, I say the plants communicate through what we call feeling. I think it impossible to immerse yourself in nature and not feel this communication! Through being more in tune, one will understand more readily the fact of what is happening- nature is good, green is life and love, it feels good to be in nature. Why? Because the plants are communicating to us