i saw an episode of mythbusters once where they did that and they put a bunch of plants in their own little greenhouses with different styles of music playing and i think the one listening to death metal did the best, i think they concluded that it was all the bass hits in it or something...and they did on
i dont know why it posted in the middle of a sentence but whatever...they did another episode where they proved plants had feelings and based on wether you were real nice or mean to the plant it reacted differently, they used a polygraph to determine this, i thought it was pretty interesting...