Add mistletoe to the list of appropriated Christmas traditions. It turns out the plant, which is actually a parasite that grows on certain trees, made its debut as a holiday crowd pleaser in ancient Greece, where it was considered a symbol of fertility—hence the kissing. The Romans used it as decoration for peace treaties and, of course, the Celtic druids went all out in harvesting it with golden sickles in the moonlight. And it features heavily in Norse mythology:
For its supposedly mystical power mistletoe has long been at the center of many folklore. One is associated with the Goddess Frigga. The story goes that Mistletoe was the sacred plant of Frigga, goddess of love and the mother of Balder, the god of the summer sun. Balder had a dream of death which greatly alarmed his mother, for should he die, all life on earth would end. In an attempt to keep this from happening, Frigga went at once to air, fire, water, earth, and every animal and plant seeking a promise that no harm would come to her son. Balder now could not be hurt by anything on earth or under the earth. But Balder had one enemy, Loki, god of evil and he knew of one plant that Frigga had overlooked in her quest to keep her son safe. It grew neither on the earth nor under the earth, but on apple and oak trees. It was lowly mistletoe. So Loki made an arrow tip of the mistletoe, gave to the blind god of winter, Hoder, who shot it , striking Balder dead. The sky paled and all things in earth and heaven wept for the sun god. For three days each element tried to bring Balder back to life. He was finally restored by Frigga, the goddess and his mother. It is said the tears she shed for her son turned into the pearly white berries on the mistletoe plant and in her joy Frigga kissed everyone who passed beneath the tree on which it grew. The story ends with a decree that who should ever stand under the humble mistletoe, no harm should befall them, only a kiss, a token of love.
Which brings us to corvids. The mistletoe connection comes courtesy of the Ravenmaster at the Tower of London. But be wary of a peck on the cheek from one of these guys.