Contents tagged with parasite
Created: 12/11/2013 Updated: 8/9/2016
“Mistletoe is still a controversial plant. Growing between heaven and earth, never touching the ground, and not accepting the seasons.” ~ Arndt Büssing
Here in America, we commemorate the December holidays – particularly Christmas – with remarkable fervor. Numerous traditions have sprung up around the celebration of Christmas; each with their own associated imagery and accoutrements. As a horticulturist, I’m struck by the degree to which plants have become part of these customs. Sure, we might send a dozen roses at Valentine’s Day or pin a shamrock to our lapel on St. Patrick’s, but no holiday so intimately integrates plant life as Christmas. From holly to wreaths, from poinsettias to the tree in the living room, plants are very much a part of the special things we do this time of year.
Mistletoe is without doubt the most unique plant that we cherish at Christmastime, and it has arguably the most interesting and long-standing history of human use. Though the term ‘mistletoe’ is used broadly to refer to hundreds of different species of parasitic plants in the Sandalwood group, the traditional Christmas mistletoe is derived exclusively from two plants – Viscum album, native of Europe, and Phoradendron serotinum, from eastern North America. Scientists describe these plants as obligate hemi-parasites. Though they have green leaves and can thus produce their own food, they require a woody host plant to attach to, from which they extract water and nutrients via specialized root structures called haustoria.
Mistletoes, all of which are evergreen, spend their entire lives above ground. The familiar white berries of the Christmas mistletoes contain seeds surrounded by a pulp so sticky that it has historically been used to make traps for birds and small animals. Birds that eat these berries often find the pulp clinging to their beaks. To remove it, they scrape their beaks on tree branches, inadvertently leaving the embedded seeds behind. These seeds then sprout and force their haustoria into the tree to partake of its sap.
The impact of haustoria on host plants can be clearly seen in what are commonly called “wood roses.” Sometimes carved into figurines, these flower-like woody formations are actually the scars left behind by tropical mistletoe species on their tree hosts. In North America, oaks infested with mistletoe may form disorganized masses of woody tissue called galls. Other trees may develop “witches broom” deformities as a result of mistletoe attacks. In the West, these formations are preferred nesting sites for birds such as the Spotted Owl.
Though toxic to humans, many medicinal properties have been attributed to mistletoe. Herbalists have recommended it for problems ranging from poor circulation to barrenness. American Indians used it as a remedy for toothaches and to treat wounds. Ironically, some cultures used mistletoe as an antidote against poison. Recent claims of anti-cancer properties have not been substantiated by clinical research.
The singular lifestyle of the mistletoe plant must have seemed magical to many early cultures. As far back as ancient Greece, mistletoe featured prominently in Western folklore, and throughout pre-Christian Europe, it was seen as a symbol of masculinity, vitality, and fertility. The Golden Bough that Aeneas used to gain admission to the Underworld is said to have been mistletoe. The Celtic Druids believed mistletoe to be sacred, especially when growing on an oak tree. Around the winter solstice, they hung sprigs of it over their doorways to protect from lightning, fire, and other evil forces in the coming year.
Druid priests harvesting mistletoe
According to Norse legend, the goddess Frigg so loved her son Baldr that she made all things that originate from the elements promise not to harm him. But the devious Loki tricked Baldr’s brother, Hoder, into shooting him with an arrow of mistletoe. Because the tree-dwelling mistletoe did not spring from the elemental earth, Baldr fell dead, and Frigg’s tears became the plant’s white berries.
In tropical regions, where most species of mistletoe grow, legends abound. Australian Aboriginals tell poignant tales of “spirit babies,” sent to the earth to find a mother. They hide in trees waiting for a young woman to walk by, but if none will be their mother, they wail and cry until they are changed into mistletoes.
Of course, most of us know mistletoe as a seasonal license to steal a kiss. Though the origins of this practice are murky, some interesting variations exist. Some say that with each kiss, a berry must be removed from the sprig, and when the berries are gone, so are the kisses. Others say a kiss under the mistletoe indicates marriage for the couple in the coming year. In certain traditions, the mistletoe is not allowed to touch the ground, and is the last of the Christmas decorations to come down.
Holiday traditions aside, mistletoes are unique and remarkable plants. In the entire plant kingdom, their particular form of parasitism has only developed in perhaps three plant families. If you find yourself in the southern third of the state this winter, or anywhere else in the South or Mid-Atlantic, scan the bare trees for incongruous sprays of smooth green leaves. It's easy to imagine how mysterious and alluring they must have appeared to ancient peoples.