This is a video posted by the U.S. Consumer Product Safety Commission demonstrating why it's so important to keep your Christmas tree watered but igniting two seperate trees: one watered, one dry. They ignite the dry tree a full 30 seconds after the watered tree, and it burns up in a massive fireball immediately. The watered tree still seems relatively fine after a minute. Also, who the hell doesn't water their tree? It's literally the ONLY thing you have to do to take care of it. Please tell me you don't have any pets or children.
Keep going for this video, as well as another of the same experiment conducted by the National Institute Of Standards And Technology (NIST -- yay, Gaithersburg, MD).
Thanks to Hams Down, who agrees maybe some people should start considering Christmas rocks instead of trees.