If you've got a few minutes, turn up the volume on your computer and visit these links that lead to songs about plants.
This one is about invasive plant species, and all of the images were submitted by school kids...
Here is a very creative song that was posted on the blog No seeds, no fruits, no flowers: no problem. Adventures in fern biology. This song was created by college students for extra credit... http://noseeds.blogspot.com/2011/01/fern-rap.html
Finally, a classic by the band Genesis, about the nasty invasive species Giant Hogweed (Heracleum mantegazzianum)...