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Mistletoe: Blessing or Bane?
by Sarah Browning, UNL Extension Educator
One plant that is irrevocably tied to the holiday season for most people is mistletoe, bringing to mind the image of greenery hung over a doorway in anticipation of a kiss. The white-berried plant we decorate with during the holidays, commonly known as American mistletoe, is one of 1,300 or more species of mistletoe worldwide. All have a very interesting life history, including some good and some bad, so read on for a little background information about the plant behind many Christmas traditions.
Two species, American mistletoe and dwarf mistletoe are native to the United States, although this does not include Nebraska. American mistletoe is found from New Jersey to Florida and west through Texas, where it is commonly harvested and sold during the holiday season. Dwarf mistletoe, much smaller than its kissing cousin, is found from central Canada and southeastern Alaska to Honduras and Hispaniola, but most species of mistletoe are found in western United States and Mexico.
One thing that all mistletoes have in common is that they are a type of parasitic plant. In fact, the American mistletoe's scientific name, Phoradendron, means "thief of the tree" in Greek. The plant is aptly named: it begins its life as a very sticky seed that often hitchhikes to a new host tree on a bird beak or feather, or on mammal fur. (In it's native range, mistletoe berries are an important food source for many bird species.)
The plant's common name - mistletoe- is derived from early observations that mistletoe would often appear in places where birds had left their droppings. "Mistel" is the Anglo-Saxon word for "dung," and "tan" is the word for "Twig." Thus, mistletoe means "dung-on-a-twig."
For the most part, mistletoe is pretty haphazard about what host tree it finds – dwarf mistletoes like most kinds of conifers; American mistletoes are found on an incredible variety of trees.
Once on a host tree, the mistletoe sends out roots that penetrate the tree's bark and eventually starts pirating some of the host tree's nutrients and minerals. Actually scientists classify mistletoes as 'hemi-parasitic' plants, because most of them have the green leaves necessary for photosynthesis. Still, it's a pretty easy life: a little photosynthesis here and there and a lot of food and water stolen from their unsuspecting benefactor trees.
Eventually, mistletoes grow into thick masses of branching, misshapen stems, within the canopy of the host tree, giving rise to the popular name "witches' brooms", or the apt Navajo name of "basket on high." This "basket" of twigs serves as an important nesting site for many birds and squirrels.
So aside from holiday traditions, is mistletoe a bane or blessing to the natural environment? Ecologists point out that mistletoes are a native group of plants that have been around thousands, or even millions, of years and are a natural part of forest ecological systems in the southwestern U.S.
Also, a greater variety and abundance of cavity nesting birds have been documented in mistletoe-laden trees, although the lifespan parasitized trees is considerably shorter than that of non-infected trees, parasitized trees can still live for several decades. So blessing or bane? It depends on your perspective.
Photo credit: Mistletoes (Phoradendron spp.) , Paul A. Mistretta, USDA Forest Service, Bugwood.org
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