Dryad is a tree nymph, or tree spirit, in Greek mythology. Dryads, like all nymphs, were supernaturally long-lived and tied to their homes, but some were a step beyond most nymphs. These were the hamadryads who were an integral part of their trees, such that if the tree died, the hamadryad associated with it died as well. For these reasons, dryads and the Greek gods punished any mortals who harmed trees without first propitiating the tree-nymphs.