WASHINGTON—Mistletoe is more than an excuse for kissing. The

WASHINGTON—Mistletoe is more than an excuse for kissing.

The focus of elaborate Druid rites at Stonehenge and the powerful Golden Bough of mythology, mistletoe was once believed to promote fertility, protect from fire and lightning, cure epilepsy, and, some say, provided the wood for the cross of Christ.

Mistletoe, which flourishes without direct contact with earth, is probably poisonous to people, but is a mainstay of the diet of birds. Although it grows primarily in the tropics, mistletoe inflicts more damage on U. S. forests than any disease.

Tree Thief

Belonging to the genus Phoradendron, which translates “tree thief,” mistletoe is a semiparasite that grows in the tops of oak, mesquite, maple, and other trees. Mistletoe takes all its water and nutrients from the host tree, but snythesizes its own food, explains Delbert Weins, a biologist at the University of Utah who has studied mistletoe for 25 years.

“The mistletoes make up a very large, complicated genus ranging throughout the world, but only about four species in the United States are used for Christmas decorations,” he said. “These are found throughout the United States, except for the colder regions of the northern Rocky Mountains, the Great Plains, the northern Midwest, and New England.”

If mistletoe has uses other than promoting holiday cheer, they have not been found. But it is significant economically for the damage it inflicts on timber trees.

Ed Wicker, plant pathologist for the U. S. Department of Agriculture, says 3.2 billion board feet of timber growth a year is not realized because dwarf mistletoe saps vital nutrients and moisture from the trees—enough wood to build 290,000 average homes.

Early Christian legends hold that mistletoe, once a tree itself, shrank in shame after Christ’s cross was hewn from its wood. But that legend hasn't shrunk its holiday popularity in