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We May Kiss Under the Mistletoe, but are These Berries Poisonous?

Chances are you may have kissed under the mistletoe. But is it actually poisonous? Learn about its potential dangers, and if it is toxic to plants and pets.

By Sara Novak
Dec 12, 2023 7:00 PM
Festive couple kissing under the mistletoe
(Credit: New Africa/Shutterstock)


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Mistletoe is most well known for its role in helping holiday lovers steal a kiss, but this little bush is about much more than just smooching.

It might surprise you that mistletoe has a bit of a dark side in that it’s both parasitic and poisonous. Find out what mistletoe is, where it grows, and just how poisonous it is.

What Is Mistletoe?

(Credit: CUTWORLD/Shutterstock)

Mistletoe, a plant shrouded in ancient folklore, is more than just a holiday decoration. This perennial, evergreen plant thrives by attaching itself to host trees and extracting water and nutrients.

What Does Mistletoe Mean?

The term 'mistletoe' originates from the Anglo-Saxon words 'mistel,' meaning dung, and 'tan,' meaning twig. Mistletoe produces a white berry that contains a seed that birds ingest and often carry to the next plant. When a bird defecates that’s usually the site of the next mistletoe implantation, which is why mistel means “dung.”

(Credit: New Africa/Shutterstock)

Why Do People Kiss Under the Mistletoe?

The tradition of kissing under the mistletoe began in England and later spread to the U.S. The plant’s ability to survive anywhere was a sign of fertility and kissing underneath it was also thought to lead to marriage. The plants are a good fit for decorating (and kissing underneath) at Christmas because they’re evergreen and can survive even in the cold winter months.

Read More: Ancient Holiday Celebrations

What Does Mistletoe Look Like?

(Credit: riggleton/Shutterstock)

It’s also a bit of a parasite, landing on a good host and calling it home. The most common form of mistletoe is a green, waxy, broad-leaved version called American mistletoe with red berries.

Where Does Mistletoe Grow?

With over 1,300 species, the plant is found in the U.S. and Canada. Mistletoe is really common in the U.S. because it can survive on any number of trees. It’s even called Phoradendron, which means “tree thief” in Greek.

Read More: Decorate For the Holidays Early and it Might Improve Your Mood

What Tree Does Mistletoe Grow On?

(Credit: Snufkin_79/Shutterstock)

Mistletoe is not picky about its host tree. The plant can grow on birch, cottonwood, locust, maple, walnut, and apple trees.

Is Mistletoe a Parasite?

Yes, mistletoe is a parasite, that’s how it survives. If you look up into a tree, mistletoe often looks like a bush growing within a branch and that’s because it uses ornamental timber trees as a host.

Mistletoe grows on other plants, and, in some cases, can even cause abnormal pockets of growth called “witch’s brooms” that deform branches and hinder the growth of the host plant.

Does Mistletoe Kill Trees?

Mistletoe can do some damage to our arboreal friends, but it’s not likely to kill a whole tree unless it’s allowed to grow uncontrollably. As mentioned above, it can cause deformities, and, in some cases, can cause branches to die off as a result of a “mistletoe infection."

The tree may need to be pruned to remove the parasite. To remove mistletoe from a tree, you’ll need to go beyond cutting the mistletoe and cut the branch as well because its roots can extend into the tree. Using chemicals to remove mistletoe isn’t a good idea because they often don’t penetrate the roots of the plant.

Read More: Why Some Can't Get Enough Of Hallmark Christmas Movies

Is Mistletoe Poisonous?

Mistletoe is poisonous and, in fact, mistletoe poisoning can occur in humans if you eat the plant, its berries, or if you drink tea that contains it. Symptoms of ingestion can include blurred vision, diarrhea, stomach pain, nausea, weakness, and drowsiness.

If you or someone you know ingests it, you should seek medical attention immediately. While death is unlikely, a dose of mistletoe might lead to a hospital stay.

Is Mistletoe Poisonous to Dogs?

If you have mistletoe hanging from your rafters, you could be endangering your kids and your pets because it’s also toxic to cats and dogs. According to the U.S. Food and Drug Administration, the chemicals found in the plant, called lectins and phoratoxins, can impact a pet’s heart causing low heart rate and blood pressure.

Luckily, most animals are uninterested in eating the green stuff and are unlikely to take in enough to cause any real damage. Symptoms of mistletoe poisoning in pets can include tummy troubles like vomiting and diarrhea.

While we think of mistletoe as nothing more than a reason to smooch, this parasite of a plant can do some real damage to humans, pets, and the trees it calls home.

Read More: Why Reindeer Don't Fly, According to Physics

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