All mistletoes grow as parasites on the branches of trees and shrubs. The genus name of North America’s oak mistletoe—by far the most common species in the eastern United States—is Phoradendron, Greek for “tree thief.”

Ancient Anglo-Saxons noticed that mistletoe often grows where birds leave droppings, which is how mistletoe got its name: In Anglo-Saxon, “mistel” means “dung” and “tan” means “twig,” hence, “dung-on-a-twig.” Mistletoes produce white berries, each containing one sticky seed that can attach to birds and mammals for a ride to new growing sites.

The ripe white berries of dwarf mistletoe, native to the western United States and Canada, also can explode, ejecting seeds at an initial average speed of 60 miles per hour and scattering them as far as 50 feet!

Mistletoe was associated with fertility and vitality through the Middle Ages, and by the 18th century it had also become incorporated into Christmas celebrations around the world. The serving class of Victorian England is credited with first recording the tradition of kissing underneath the mistletoe. The tradition dictated that a man was allowed to kiss any woman standing underneath mistletoe, and that bad luck would befall any woman who refused the kiss. One variation on the tradition stated that with each kiss a berry was to be plucked from the mistletoe, and the kissing must stop after all the berries had been removed.

The ancient Celts believed mistletoe to have miraculous healing powers: the power of healing diseases, making poisons harmless, giving fertility to humans and animals, protecting from witchcraft, banning evil spirits, and bringing good luck and great blessings. In fact, it was considered so sacred that even enemies who happened to meet beneath a Mistletoe in the forest would lay down their arms, exchange a friendly greeting, and keep a truce until the following day. From this old custom grew the practice of suspending Mistletoe over a doorway or in a room as a token of good will and peace to all comers.