Chances are, holiday revelers will find themselves underneath the mistletoe at least once this holiday season. While they might know what to do when that time comes, they might not know the history of that plant above their heads.

Especially sacred to Celtic Druids, mistletoe was believed to bestow life and fertility, while also protecting against poison and serving as an aphrodisiac. Mistletoe would later take on a more political meaning, as the ritual of cutting the mistletoe symbolized the emasculation of the old King by his successor.

Nowadays, mistletoe is typically hung in doorways or entryways from one room to another. This tradition can also trace itself back several centuries to the Middle Ages. During the Middle Ages, branches of mistletoe were hung from ceilings to ward off evil spirits. Throughout Europe, mistletoe was placed over doorways in the house as well as the stables as a means to prevent the entrance of witches.

The tradition of kissing underneath the mistletoe likely stems from the belief that mistletoe bestows fertility and is often associated with the Roman festival of Saturnalia, a period of merrymaking that pre-dated Christmas. In 18th century England, a young lady standing underneath the mistletoe could not refuse to be kissed. Once kissed, the kiss would signify deep romance or eternal friendship.

History also suggests that mistletoe was a symbol of peace. In Scandinavia, mistletoe was considered a plant of peace. When standing underneath the mistletoe, enemies could declare a truce and spouses could end any marital turmoil with a kiss.