He never left his roots behind--the roots are still there, hidden at the foot of the mountains (beneath which the King sleeps, until he should come again one day).
Perhaps you can find these roots, if you journey to the Well at the World's End, or the Wood Beyond the World, or sail on the Water of the Wondrous Isles.
But he is, after all, a modest fellow. He hides his light under a bushel.