Kissing under the mistletoe was first associated with Greek celebrations, and later primitive marriage rites in which mistletoe was thought to have the power of bestowing fertility. Scandinavians considered mistletoe a plant of peace, under which enemies could declare a truce or disgruntled spouses could "kiss and make-up." Mistletoe is burned on Twelfth Night in various regions of England in the belief that men and women who kiss underneath it will marry.
Mistletoe is considered an aerial parasite with no roots of its own, living off of the tree it attaches itself to. Without the tree, the mistletoe will die. In history, the Celtic people once thought mistletoe harbored miraculous healing powers. In the Celtic language "mistletoe" translates to "all heal." It is said the curing "powers" of mistletoe not only arrested diseases, but could render poison harmless, keep people safe from witchcraft, protect the house from ghosts and even make the ghosts speak. It was also considered good luck to have possession of the mistletoe.
There are two types of mistletoe. The variety in the United States (Phoradendron flavescens) is native and grows on trees mainly from New Jersey to Florida. The second type of mistletoe (Viscum album) grows in Europe and is typically a small green shrub with yellow flowers and sticky berries which are considered poisonous.
In the Middle Ages and later, branches of mistletoe were hung from ceilings to ward off evil spirits. In other parts of Europe, they were placed over house and stable doors to prevent the entrance of witches. It was also believed mistletoe that attached to oak trees could extinguish fires, and in parts of England farmers would give a Christmas bundle of mistletoes to the first cow that calved in the New Year. It was also thought to bring luck to the entire herd.