By Val Whitmyre, U. C. Master Gardener

Mistletoe

It is a mystery why mistletoe is associated with kissing at Christmastime, but some sources claim that it started in ancient Europe when primitive people began to notice all the benefits trees afforded them, such as heat, shade, food and shelter. Particularly revered was the oak tree.

In winter, these people noticed leafy mistletoe growing on bare oak branches. They believed that the mistletoe was somehow keeping the oak alive through the winter, so they concluded that mistletoe had magical powers. In fact, some early Europeans worshipped mistletoe and hung it on their front doors to ward off evil spirits. In rural areas, they hung it over stable doors to protect animals against witchcraft.

For more than 2,000 years, people have suspected that mistletoe had medicinal benefits. In Sweden and Italy. mistletoe was thought to have the power to prevent and extinguish fire. In other countries, people used mistletoe in rituals to find treasure.

There are indications that mistletoe was incorporated into the Christian religion after the third century, with some people believing that kissing underneath it promoted fertility. So depending on your beliefs, hanging a sprig of mistletoe in your home would enhance your health, safety, fortune or family—or perhaps all of the above.

The Phoradendron genus is the type of evergreen broadleaf mistletoe we usually see in the valley. Phora means thief in Latin and dendron means tree. This gives you an idea of how mistletoe grows.

Mistletoe is a perennial flowering parasitic plant that thrives until its host tree dies or the branch on which it grows dies. Mistletoe seldom damages the host branch unless there are many plants on one branch, which may be debilitating and require removal of the entire branch. If any mistletoe is left on the branch, it will regenerate.

The tiny mistletoe flowers are inconspicuous and without petals. Only female mistletoe produce fruit—small white berries covered with a watery, glue-like substance that helps mistletoe establish itself on a tree branch. Berry-eating birds distribute mistletoe seeds from branch to branch and from country to country. The birds' warm, moist digestive systems make perfect germination facilities.

The seeds' sticky exterior helps them adhere to branches. Some birds rub their beaks on a branch to rid them of the sticky substance, or they may preen their feathers to remove the sticky berries.

After the bird deposits the seed, a tiny root-like radicle develops from the seed and travels along the bark until it finds an irregular spot. There it cements itself onto the branch with an airtight seal. Next, it pierces the bark to reach the "indoor plumbing" level called the phloem. At that point, the tree will begin to supply the mistletoe with water and nutrients.

The young mistletoe plant is able to photosynthesize and supply all of its carbon needs, so with the help of the host tree, it will have all it needs to grow. In about a year, the plant will form leathery green leaves and small pearly-white seeds. The leafy mistletoe cannot live without the host tree, but it seldom deprives the tree of its vigor. The berries and leaves of the plant are toxic to people. Birds are unaffected and so mistletoe continues to thrive.

Luther Burbank imported European mistletoe, the Viscum genus, into California in the 1900s. Since then, it has spread to 24 tree species, including the willow, alder, poplar, elm, mountain ash, crabapple and pear. This plant is certainly a fascinating historical and horticultural oddity, but the custom of kissing under the mistletoe remains an innocent and friendly tradition. I hope it continues.