 Mistletoe is an evergreen plant well known for its association with oak trees and Druids first documented by Pliny the Elder who wrote about the ceremonies of the Celtic Druids in Gaul in his "Naturalis Historia".These Druids held the oak in particular veneration, used oak leaves in their ceremonies, and regarded anything growing on oak trees as having been sent from heaven.On the rare occasions when mistletoe was found growing on an oak, it would be gathered with great ceremony.