A lot of people decorate with mistletoe around the Christmas holiday. Many hang it from the ceiling or over a door and offer kisses to those who stand under it. But have you ever wondered why? How did mistletoe come to be associated with kissing in the first place? Here’s what we know, along with some other interesting trivia about what many consider to be the most romantic Christmas symbol.

As a starting point, you should know that mistletoe is actually a parasitic plant—as a result, it’s not something you’d actually want growing in your own back yard! Basically, what mistletoe does is penetrate the branches of a tree, giving it the ability to steal nutrients and water. This allows a mistletoe plant to grow and thrive, while the host tree suffers.

Mistletoe is a species of phoradendron, a name that literally means “tree thief” or “thief of the tree” in Greek, reflecting its parasitic nature. Given that mistletoe is characterized as tree “thief," it kind of makes sense that, as a holiday decoration, this theme of thievery has carried over, with mistletoe now being used as an excuse to "steal" kisses (it's not exactly stealing, though, because people standing under the mistletoe obviously have the right of refusal).

Mistletoe can grow just about anywhere. There are some species of it that grow in the desert, and others that thrive in the dead of winter. Given that it’s such a hardy plant, it shouldn’t be surprising to learn that mistletoe has a very long history of being viewed as a symbol of fertility. In fact, in some cultures, mistletoe was viewed as much more than just a symbol and was even used as a treatment for infertility for both humans and animals. Mistletoe’s link to kissing is believed to stem, at least in part, from this longstanding association with fertility—however, it’s also worth pointing out that mistletoe played a pivotal role in ancient Norse folklore, in which the gods declared this plant to be a symbol of love and life.

In the last few hundred years, mistletoe went from being a sacred plant that promotes health and fertility to a holiday decoration that inspires kissing. How exactly that happened, we can’t say for sure; however, now that you have some sense of the history of mistletoe’s symbolism, this transition probably makes a little more sense.

Here’s one other interesting piece of mistletoe trivia that ties it in with science: in modern times, mistletoe isn’t just used as an excuse for kissing—it continues to be used as a medicinal plant in some parts of the world. In fact, in some European countries, mistletoe extract is one of the most common medicines prescribed to patients who have cancer! Despite its popularity in Europe and some research suggesting that mistletoe can kill cancer cells, it is not FDA approved for use in the United States (learn more about mistletoe as a cancer treatment here).

Bet you won’t look at a sprig of mistletoe the same way again. Happy Holidays!

Want to learn more about Sex and Psychology? Click here for previous articles or follow the blog on Facebook (facebook.com/psychologyofsex), Twitter (@JustinLehmiller), or Reddit (reddit.com/r/psychologyofsex) to receive updates.

Image Source: 123RF/Darya Petrenko

You Might Also Like: