I read an interesting article "The Intelligent Plant" written by Michael Pollan and published in The New Yorker. According to the article, plants have the ability to sense and react to the world. For instance, when plants were played a recording of a caterpillar chewing on a leaf, they reacted by secreting a defensive chemical, just as though they were threatened. Pollan also states that plants can sense gravity, the presence of water, and can adjust/shift the direction of growing roots when it senses there is an obstruction (a rock, perhaps).
The Discovery Channel’s Mythbusters explored the possibility that plants respond to sound and/or speech. They set up seven greenhouses, four of which were equipped with stereos playing looped recordings. Two were of negative speech, while two were of positive speech. The fifth greenhouse had classical music playing, while the sixth had heavy death metal. A seventh greenhouse, set up as the control, had no music. The team found that the plants in the four greenhouses with recordings grew faster than the control plants with no music, but the plants in the greenhouses with music grew even faster than the negative and positive speech. Surprisingly, the plants in the greenhouse exposed to heavy death metal music grew the best of all!
Bottom line: Talk and sing to your plants; complain, yell, and scream...just don't give them the silent treatment.
New Yorker article "The Intelligent Plant"
Discovery Mythbusters (Episode #23 aired November 15, 2004)
Pictured: Daylily 'Black Falcon Ritual'