With the Christmas season upon us, it is time to finish decorating homes and continue traditions that have been passed from generation to generation. One tradition that is very popular during the Christmas season is that of kissing underneath the mistletoe. Mistletoe is a symbol of life, love, and even fertility. However, have you ever stopped to think what mistletoe is and where it comes from?

Mistletoe is an evergreen that grows out of tree limbs. It is hidden by tree leaves for most of the year but balls of mistletoe become very apparent after leaves have fallen in late fall. Mistletoe is a hemi-parasitic plant that grows out of many tree species. Unlike fully parasitic plants, mistletoe has the ability to make its own energy stores which it takes up through photosynthesis. Mistletoe does, however, rely on its tree host for water and other nutrients. To get the nutrients it needs from its tree host, and to cling to the tree, mistletoe uses specialized roots called haustoria which penetrate the tree tissues and hold it in place.

As mistletoe is hemi-parasitic, it can weaken trees by siphoning off water and other nutrients. Most trees can withstand these mistletoe freeloaders without any negative effects. However, trees that have large numbers of mistletoe plants within them, or trees that are stressed from other factors, will weaken over time. If your tree is weak and you are afraid that mistletoe will be the straw that breaks the camel’s back, it may be time to remove mistletoe. To properly remove mistletoe, you must prune out the branch that it has been colonized to the point where you remove all visible shoots and the largely invisible mistletoe roots. Simply removing mistletoe shoots from the tree branch will leave the roots which can re-sprout, just like weeds in the garden. It is, however, unnecessary to remove mistletoe from every tree in sight as that mistletoe is an important part of the ecosystem.

Mistletoe relies on birds and mammals to spread from one location to another. Animals eat the white berries of mistletoe and later excrete those seeds while they are up in trees. While birds are the most common animal taking advantage of the berries, there are many other animals and insects that use mistletoe. Birds will nest within the mistletoe, bees use nectar from mistletoe flowers, and the great purple hairstreak butterfly relies on mistletoe for its larvae’s sole food source. Most mistletoe is found high in trees where birds rest or roost after eating mistletoe berries. Getting this mistletoe out of trees can be very challenging and has become a tradition in itself.

There are many species of mistletoe that live on different species of trees and inhabit varied regions of the United States and world. While there are many species, North American mistletoe is broken down into two main groups. Dwarf mistletoes are largely leafless and tend to colonize species of pine, firs, and other conifers. Dwarf mistletoe is in the genus Aurceuthobium and is generally not used for our holiday traditions. The leafy American mistletoe species are within the genus Phoradendron and tend to colonize many deciduous tree species such as oaks, maples, ash, hickory, and elms. Phoradendron leucarpum is the mistletoe species found in the southeast and can make beautiful Christmas decorations.

Similar to poinsettia, mistletoe leaves and berries are mildly toxic if ingested. Mistletoe clippings from the yard and mistletoe decorations should be kept away from curious children and pets. If ingestion occurs, contact a poison center helpline immediately.