The Truth about Mistletoe

This California oak tree is hung with much more mistletoe than most people dangle from their doorways during the holidays. And there's a reason. Mistletoe is a parasite. Sort of.

It grows on the branches of trees and shrubs. The American mistletoe's scientific name, Phoradendron, means "thief of the tree" in Greek. The white-berried Christmas mistletoe commonly adorning winter homes in the United States is just one of more than 1,300 species worldwide.

Once on a host tree, the mistletoe sends out roots that penetrate the tree and eventually starts pirating some of the host tree's nutrients and minerals. In actuality, though, mistletoes are not true parasites; instead they are what scientists call "hemi-parasites" because most of them have the green leaves necessary for photosynthesis.

The plant's common name is derived from early observations that mistletoe would often appear in places where birds had left their droppings, according to the U.S. Geological Survey. "Mistel" in the Anglo-Saxon word for "dung," and "tan" is the word for "Twig." Thus, mistletoe means "dung-on-a-twig."

Mistletoe is an integral part of a healthy forest. Birds nest in it. The great purple hairstreak, a butterfly, feeds on it. Bees often depend on it for the first pollen of spring. Elk and deer eat the berries in winter when other food is scares.

Kiss under the mistletoe, but don't kiss it. The berries are toxic to humans.

• Not So Nice: A Naughty Type of Mistletoe

-- LiveScience Staff

Image credit: USGS