According to Celestia, the tree controls and contains all that grows in the Everfree Forest, even without the Elements in it. Twilight Sparkle and her friends discover that the Tree of Harmony has lost its magic, allowing Discord's plunderseeds to sprout and grow all over the Everfree Forest, slowly killing the tree. Twilight and her friends give up the Elements of Harmony and return them to the tree, recharging its magic and restoring the forest.