Mistletoe and Ivy
Anyone who has spent any time at all studying the ancient druids has learned that the druids held the mistletoe plant in very high esteem. Classical writers, especially Pliny, point out that of all the plants of the forest, the druids most revered mistletoe. He describes a mistletoe collection ritual, where, on the “sixth day of the moon,” the plant is cut with great ceremony using a sickle-bladed knife:
For they believe that whatever grows on these trees is sent from heaven, and is a sign that the tree has been chosen by the gods themselves. The mistletoe is very rarely to be met with; but when it is found, they gather it with solemn ceremony. This they do above all on the sixth day of the moon, from whence they date the beginnings of their months, of their years, and of their thirty years cycle, because by the sixth day the moon has plenty of vigor and has not run half its course.
After due preparations have been made for a sacrifice and a feast under the tree, they hail it as the universal healer and bring to the spot two white bulls, whose horns have never been bound before. A priest clad in a white robe climbs the tree and with a golden sickle cuts the mistletoe, which is caught in a white cloth. Then they sacrifice the victims, praying that the gods will make their gifts propitious to those to whom they have given it.
The mistletoe grows high in the branches of trees, especially the sacred oak, with no visible source of sustenance. For this reason, and due to its golden hue and waxy white fruit, the mistletoe was believed to literally sprout from the sperm of the sun. Because of this solar association, mistle-toe was held to be a healing plant and attributed power over numerous ailments. It was so highly regarded as a magical plant that even centuries after the last druid vanished from the earth, the herb was known as “all-heal” and served as a charm against fires and lightning.
After a time, even the church intervened to try and stem the enthusiasm for mistletoe, and it was banned from use in churches. Nevertheless, the plant remained a popular charm and is still part of holiday traditions to this day.
While ivy isn't usually considered to be a tree, it was counted as one among the Celts. Ivy was given the reputation as the strongest of all the trees. Although it appeared unassuming, it was hardy and persistent, and although its growth was slow, it could eventually strangle even the strongest oak. Ivy was also counted among the sacred evergreens and was associated with resurrection and the Otherworld.