Mistletoe features in the mythology of several cultures. It is a parasite that grows on a variety of trees, including the apple and the oak. Because mistletoe remained green throughout the winter when the sacred oak was without leaves, it was assumed that the plant contained the life, the magical essence, of its sacred oak. During medieval times it was also known as Allheal and was used to treat numerous illnesses.

Oak mistletoe was worn around the neck, or its powdered berries were added to wine, water, or milk, and were drunk for the treatment of epilepsy (seizures) and was also prescribed for heart disease,high blood pressure, rheumatism, and tumors. (Warning: the plant is actually quite toxic and should be kept safely away from children and pets!)

Mistletoe's association with peace and good will is so strong that once, if enemies met under a tree that by chance had mistletoe, they were required to lay down their arms and declare a truce until the following day.  The strongest connection between mistletoe and the Yule season comes from Norse mythology. Frigga (also known as Freya) was the goddess of beauty, love, and marriage. Wife of the powerful Norse god Odin, Frigga was a sky goddess, responsible for weaving the clouds, and therefore responsible for rain and for thunderstorms.

Her sacred animal was the goose, and in her Germanic incarnation as the goddess Holda or Bertha, she was the original Mother Goose (causing it to snow when she shook out her bedding). Sitting at her spinning wheel weaving the fates, she was also a goddess of divination and credited with the creation of runes...more precisely she was a 'seer', one who knew the future but could never change it or reveal it to others.

Frigga was the mother of Baldur (Balder), the best loved of all the Norse gods. And she foresaw his death. Knowing that there was nothing she could do to avert his fate, the hapless goddess extracted a promise from all things that they would play no part in his death. Unfortunately, thinking the mistletoe was too insignificant to bother with, she neglected to secure its pledge.

And when the malevolent prankster Loki discovered her oversight, he crafted a dart made of the poisonous plant. Devious and evil, he brought it to Baldur's brother who was blind, suggesting a game of darts and agreeing to guide his hand. And this he did, directing the dart directly at Baldur's heart.

The mistletoe's white berries were formed from Frigga's tears of mourning. Some versions of the story of  Baldur's death end happily. Baldur is restored to life, and the goddess Frigga is so grateful that she reverses the reputation of the baleful plant, making it a symbol of peace and love and promising a kiss to all who pass under it.

Mistletoe is also thought to be the "golden bough" of Virgil's Aenid, a plant that once offended the gods and was cursed to have to look on while beautiful girls were being kissed. In Rome mistletoe played a role in the Saturnalia, festivals held during the Yule season to celebrate the birth of Saturn. The tradition of kissing under the mistletoe (and removing one berry with each kiss until none remained) emerged from that fertility rite. This may explain why, unlike other pagan traditions, banning the plant from churches is still widely practiced even today.

The Druids (British) also revered the plant's powers as an aphrodisiac, believing the berries to contain the sperm of the gods. On the sixth night of the new moon of the winter solstice, they would use a golden sickle to cut the mistletoe from the sacred oak, letting it fall into a cloth held under the tree by members of the order so that the sacred plant would not touch the ground. The Chief Druid would  cut off sprigs for distribution to the people, who hung them over their doorways for protection against thunder and lightning.