January 18, 2022

Kissing under the mistletoe — a holiday favorite with a dark side

From evergreens and poinsettias to holiday cacti and holly, we use a variety of different plants to adorn our homes and offices during the holidays. One plant that is commonly talked about is mistletoe. Mistletoe has an interesting past, from an ancient symbol of fertility to somewhere to sneak a quick kiss. It also has a darker side.

Mythology and folklore Druids would climb a sacred oak tree and remove mistletoe with a golden sickle. After obtaining the mistletoe, they would sacrifice two white bulls to their gods. They would then make an elixir with the mistletoe and believed it would cure infertility as well as being an antidote to all poisons. Other cultures also associated mistletoe with fertility because it bears fruit in the winter. In Austria, mistletoe was placed in couples’ beds to encourage conception. In Japan, the Ainu would chop up mistletoe and put it on their fields to ensure a good crop. Welsh farmers believed that a healthy crop of mistletoe would mean they would have a good crop next year.

Why do we kiss under mistletoe?

No one knows for sure why we kiss under the mistletoe. However, Washington Irving is responsible for the popularization of kissing under the mistletoe in the United States. In his collection of essays, “The Sketch Book of Geoffrey Crayon, Gent”, he wrote about Christmas traditions he observed in an English country house, including kissing under the mistletoe.

Freeloading parasite

Mistletoes are hemiparasitic plants, which are commonly evergreen. They will obtain water, nutrients, and minerals from their host plants. They are considered hemiparasitic because they can produce their own “food” via photosynthesis during at least some point in their lifetime.

Birds commonly spread mistletoe. Birds will eat the plants’ berries and eventually pass through the bird. The seeds are sticky, thanks to a coating of viscin. If a seed lands on a tree, the seed will germinate and penetrate its host. It will then produce a special structure called a haustorium, which will act like a root, allowing the plant to begin its life of thievery. In the United States, the mistletoe species that people are probably most familiar with, and the type we decorate with, is American/eastern/oak mistletoe (Phoradendron leucarpum). It can be found from New Jersey to Florida and west through Texas, including in Illinois, where it can be found in the southern one-sixth of the state. It can be found on over 60 species of trees, including maple, ash, walnut, oak, elm, willow, and oak.

Toxic berries?

There is a common belief that mistletoe is poisonous, even deadly. This is certainly true for the European species (Viscum album). It appears that American mistletoe is less toxic than its European cousin. One study found that 99.2% of those exposed to mistletoe had no poisoning symptoms, and there were no fatalities. And that the accidental ingestion of American mistletoe is not associated with profound toxicity.

Regardless of its apparent lack of toxicity, it’s still a good idea to keep these plants out of the reach of children and pets. You can always go the route of artificial mistletoe.

Kenneth Johnson is a University of Illinois Extension educator, horticulture.