Sacred trees (synonyms: holy trees; example mythonyms: the Holy Elm) are trees that carry particular significance in a fictional world. They may have religious significance, they may mark a treaty between nations, they may be located at important historical sites. There may be a single tree, or there may be a sacred grove. If the tree is large, it may be a giant tree or a world tree. In fantasy worlds, sacred trees may be magical, or their components (bark, seeds, leaves) may have magical properties. The planting or death of sacred trees may mark the beginning or end of an era. Sacred trees may be found in a temple, castle, or in a spirit land. They may be guarded.