CM7, The Tree of Life, from TSR, 1986. In this scenario, elven player characters go on a quest to the grave of the first Tree-keeper to find the cause of the disease which is killing the Tree of Life.
The Feadiel clan's Tree of Life is dying. The best warriors in the clan are recruited to cure the tree; if it dies, all the elves will perish as well. The elves soon go to the deepest part of ancient Selinar, Elvenhome, to find the guarded grave of the first Treekeeper. An interesting idea, but it most likely won’t be a part of an existing campaign, as all the characters must be Elves (not that there’s anything wrong with that).