A parasitic plant with potentially toxic berries might not sound like it’s taking your Christmas decorations to the next level. But, botanically speaking, it is mistletoe.
There are about 1,300 species of this evergreen plant worldwide. Both are parasitic or semi-parasitic, meaning they can only live on host plants. They are not rooted underground, but live on the branches of other trees and shrubs.
Only two types are native to North America. Twelve species of American mistletoe can be found mainly in the southern half of the United States, mainly affecting deciduous trees in the east and some evergreen plants in the west. Sixteen species of leafless dwarf mistletoe infect only trees in the pinaceae family, mainly on the West coast.
American mistletoe is an American Christmas plant of the genus Phoradendron, Greek for “tree thief.” It has green leaves and is capable of photosynthesis, so it can produce most of its own food. But American mistletoe also draws water and other nutrients from its host plant by feeding root-like structures called haustoria into branches and vascular tissues beneath their bark. Even when the mistletoe plant itself is removed, these invasive structures can survive in the tree for many years.
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Mistletoe is what botanists call dioecious, meaning there are separate male and female versions of the plants. The fruits produced by females, called berries, are usually white, but can be pink or reddish depending on the species. Birds spread seeds widely after eating berries. The seeds of some species can also be shot out of the fruit like cannonballs at speeds of up to 60 MPH (100 km/h) over distances of up to 50 feet (15 meters). The sticky material on the seeds helps them stick to whatever trees they land on until they germinate and start growing.
In general, mistletoe will not kill a tree unless it is heavily infected. Even so, trees don’t usually die from mistletoe. In most cases, death is an indirect effect of disease or insect attacks that take advantage of pressurized trees. Mistletoe’s parasitic manner can cause significant economic losses to forests that are industrially harvested for timber.
For homeowners, however, there is usually no need to control mistletoe — which is good, as getting rid of it can be difficult and requires patience and persistence. You can trim it off, make sure to set aside all those haustoria scattered under the bark of the host, or try chemical control methods such as plant growth regulator ethephon.
You may want to trim a twig for Christmas decorations. Dating back to at least the 1700s, one of the most common traditions associated with mistletoe is that anyone wandering under it welcomes a festive kiss. In my home state of Oklahoma, mistletoe is our state flower symbol, apparently because during the particularly harsh winter of 1889, it was the only green plant that could have been used for a grave. In other parts of the world, mistletoe is believed to give life and fertility, as a peace offering and protection from poison.
About poison: Mistletoe is known as a poisonous plant. While European species of mistletoe are reported to be poisonous, American mistletoe is not deadly. However, it’s best to keep it away from children and pets, and use artificial mistletoe for decorations if you’re worried.
Mistletoe is an important part of the north American ecosystem. Many birds rely on mistletoe berries as a food source, as do elk, deer, squirrels, chipmunks and even porcupines, which also eat leaves when other fresh leaves are scarce. Tangled mistletoe, traditionally known as a witch’s broom, provides nesting sites for birds, including spotted owls and Cooper’s hawks, among other animals. Three species of butterflies in the United States rely entirely on mistletoe. It is also an important nectar and pollen plant for honeybees and other native bees.
As a result, the parasitic plant plays an important role in both ecosystems and human traditions. If it grows near you, enjoy it, because you may not be able to get rid of it completely anyway. It might come in handy during the Christmas season.