Trees often act in caring, altruistic ways with one another. Trees are able to share water and nutrients with those of the same species- and they often do, even when a fellow tree is only a stump in the woods with no hope of recovery.
This phenomenon has been documented in many parts of the world, where trees have continued to live after being cut down, supported underground by nearby tree friends. (source)
This is a fascinating documentary on the intelligence of plant and trees: