You can talk to plants and make them happy ... yup, and likely they can return the favor!  
Did you know that Francis Darwin specialized in Plant Physiology ... and stirred the pot just like his dad did. Apparently both Charles and Francis were proponents of the idea that plants were intelligent.

This is field is starting to pick up steam! check

Brilliant Green: The Surprising History and Science of Plant Intelligence  by Stefano Mancuso.

Turns out Francis wasn't terribly shy ... Brilliant Green recounts Francis Darwin's opening gambit ...
on September 2, 1908, at the opening of the annual congress of the British Association for the Advancement of Science, he threw caution to the wind and declared that plants are intelligent beings.
also, take a look at A lot was motivated by Barb's Nobel Prize talk -  McClintock, B. (1984). The significance of responses of the genome to challenge. Science 226, 792–801. doi: 10.1126/science.15739260 there's more to this story ... check later .