The Liberty Tree
This started as a comment on Ogre's site, but then I found pictures:
Why did old trees become symbols of liberty and freedom? Why New England? Why Deacon Elliott's elm tree in particular? Part of the answer, no longer obvious today, may be found in the appearance of a mature American elm tree. Before the twentieth century, when Dutch elm disease ravaged this species, an ancient elm was an inspiring sight. Its limbs soared upward in long sweeping curves, like the tracery of a Gothic cathedral. A massive trunk and gnarled bark made it a symbol of great age. Elms were thought to be more durable than most mortal things. London Bridge was built of elmwood that was thought to last a thousand years. Early Christians worshipped beneath elms that became emblems of eternal life. (Liberty and Freedom, by David Hackett Fischer, p. 24)
Compare a row of healthy trees,

to a row of trees ravaged by Dutch Elm Disease:

Unfortunately, it isn't only our symbol of liberty that has become diseased.

And don't forget that the roots are planted in the home. So don't forget to submit to the Carnival of Homeschooling!

Photo credits:
American elm, by Joseph O'Brien
Dutch Elm Disease, by Joseph O'Brien