Horticulture News: True nature of mistletoe

By Kim Cowherd, Published:

Now that the leaves have fallen, mistletoe becomes highly visible on large trees throughout Kentucky.  Phoradendron, the scientific name for this parasitic plant, means tree thief.  John Hartman, UK Plant Pathology Professor, tells us more about this interesting phenomenon.

You can commonly find these small leafy plants on twigs and branches of many hardwood species in the southern two-thirds of the United States.  Mistletoes extract water, mineral elements and food from their host tree by way of a parasite nutrient-uptake organ; hence the name, tree thief. 

Mistletoes’ use in holiday traditions has roots in pagan times.  Its parasitic nature and the fact that it appears to be alive while the host tree appears dead, led some to believe mistletoe mysteriously held the life of the tree during winter.  Druids harvested mistletoe in a special rite, never letting the plant touch the ground, then hung it in their homes for good luck. 

There are various myths and tales around the holiday tradition of kissing under the mistletoe. Our modern-day mistletoe holiday tradition may originate with a mythological Norse goddess of love and beauty.  Frigga, whose son was restored from possible death by mistletoe, was thought to bestow a kiss on anyone walking beneath one. Today, when two people meet under the mistletoe, tradition suggests they must exchange a kiss for good luck.  

Another interesting fact is that mistletoe is the official floral emblem of the State of Oklahoma. Though history about the adoption of Oklahoma’s floral emblem may be lost, it’s reported that the mistletoe served to decorate settler’s graves when no other flowers were available.

Perhaps more generally, the color of the evergreen mistletoe throughout the winter is said to symbolize the perseverance of early settlers. In fact, the green of its foliage and the white of its berries serve as the official colors of the Oklahoma today.

Phoradendron, the most common mistletoe growing in Kentucky, resembles another species that grows in Europe.  It has simple, fleshy green leaves arranged oppositely on the stem.  Stems are short and more branched than the host tree, so mistletoe often appears as a spherical bunch of dense vegetation.

These bunches may be a foot or two in diameter and are located high in the tree for better sunlight exposure.  Mistletoe berries range from white to straw-colored to light red.  Birds eat the fruits, then deposit the seeds onto branches where they germinate and penetrate the host tree. 

Mistletoe berries are possibly toxic to humans, more often toxic to small animals. Always keep mistletoe and other holiday plants out of the reach of children and pets.

Since birds tend to roost in open-grown trees, mistletoes do not appear as frequently in forest trees.  Generally, they do not cause much damage, although they can be harmful to a tree already under stress.  If mistletoe appears on landscape trees or other trees in the urban forest, you can control it through pruning. 

More information on mistletoe can be found by logging on to: http://www.uvm.edu/pss/ppp/articles/mistlmyths.html. For more information about tree parasites and diseases, contact the Franklin Cooperative Extension Service at 695-9035 or email DL_CES_Franklin@email.uky.edu.

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