‘Tis the season … for mistletoe

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The RoVing Naturalist

By Dennis Prichard

A starling flew to a branch of an oak tree and began scraping the sticky fruits from its beak. Seeds within the small, whitish flesh were jammed into crevices in the rough bark and thus were planted. Upon germination, a small adhesive “foot” would anchor the seedling to its host. The life of a new mistletoe plant had begun.

This rather strange plant, with its even stranger lifestyle, wove its way into the minds of early civilizations and took on some very quirky attributes. The many legends that involve mistletoe in folklore and mystery have been so strong that they overshadow the true nature of this fairly common plant. One story tells of Norse gods protecting their son from danger by ordering all earthly objects not to harm him. Even so, the mistletoe was overlooked in this decree. An evil god manufactured a spear using mistletoe and slew the young god.

Although it was put to evil purpose in this legend, a sprig of mistletoe is now used in Scandinavian doorways to ward off evil spirits. Rings made from it are worn to prevent illness. And of course we hang it over our doorways at this time of year to coax otherwise hesitant suitors to plant a kiss on his intended, just for good luck.


Mistletoe was wrongly named until 1847. Botanists learned that American mistletoe was not the same as the European variety. The Old World name of Viscum album was dropped for Phoradendron, a genus not appearing in Europe.

Click to enlarge.

It is a parasite of trees – an ecological role that relatively few other plants can lead. This is due in part to the haustorium, a highly specialized root system that can burrow into wood and absorb nutrients from its host. Most times this will not affect the tree, but certain individual trees seem to be more susceptible to mistletoe parasitism. Several large clumps sometimes cover one tree while other trees nearby will have little or no mistletoe growing on them.

There are more than two hundred tree species identified as hosts. Each type of mistletoe is specific to the host tree as the parasite takes on the appearance of the host’s leaves. Juniper mistletoe has conifer-looking leaves while those on oaks have a distinctive leaf pattern mimicking that particular type of oak.

Male and female mistletoe plants are separate. The female produces the flowers and later the sticky seeds that are collected for Christmas decorations. The seeds are poisonous to humans but are relished by several kinds of birds. These fruits help hold the birds over the winter providing needed nourishment when all other berries have long since been devoured.

One of these fruits passes through the digestive tract of a robin and is scarified by an acid bath. This is essential for the seed to germinate. It is “planted” high on a limb with a proper amount of fertilizer. The seed’s travel from the parent plant has been a long and eventful one of several miles. Thus, competition  from other seeds for a foothold is less. In time, the seed splits and the next generation of mistletoe is born.

Dennis Prichard is a retired park ranger. He’s worked and studied wildlife at many National Parks and Wildlife Refuges including Carlsbad Caverns, Mammoth Caves, the Everglades, Sequoyah NWR in Oklahoma, Sevilleta NWR in New Mexico, and Isle Royale National Park, to name a few. He travels in a fifth wheel with his wife and dog, a Labrador named Cricket.

 


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Pdpatt

Very interesting! I didn’t realize it was a parasite.