For many years, throughout northern Europe, holly and mistletoe were prized during the bitter winter months for their evergreen character, symbolizing life and continuity in a period of hardness and want. Today, they have a cherished place as holiday greenery, brightening the winter holidays and the shortest days of the year.
Mistletoe is characterized by a distinctive forked branching habit, small leathery oval leaves and pearl white berries. It is hemiparasitic, meaning that it relies on a host plant for certain nutrients and water, but it is also capable of photosynthesis. In the wild, its host plant is a deciduous tree. Mistletoe often goes unnoticed, except in the winter months when it can be seen as a ball of green foliage among the high leafless branches of the host tree.
The juvenile plant grows by photosynthesis until its roots can penetrate the bark of the tree, drawing water, minerals and some nutrients. Unless the tree is unhealthy or heavily infested, mistletoe is unlikely to affect its health.. In fact, studies have shown that mistletoe enhances biodiversity by providing a year-round nesting place and a valuable winter food source for a wide array of birds. In a cunning bit of mutual advancement, the birds help to disperse the plant by ingesting the berries, then excreting or regurgitating the hard seed high in another tree.
Mistletoe's earliest traditions are in Norse mythology. The plant was considered poisonous because the beloved god Balder was killed by an arrow fashioned from mistletoe. The old legend has some wisdom for today. The berries are poisonous or at least likely to cause some gastric distress if eaten. When we hang a sprig of mistletoe, the leaves are real, but the berries are generally plastic. Better to compromise a holiday custom than to risk poisoning our pets and small children.
We are all familiar with the custom of kissing under the mistletoe, and for many years the plant provided a harmless excuse for a public display of affection which would otherwise have been strictly taboo. Perhaps the fact that it is now socially acceptable to kiss in public has been a factor in mistletoe's declining popularity.
The American mistletoe industry is centered in Texas, and it is under particular stress due to the drought of the past two years. Mistletoe is harvested by means of a long hook, although many years ago it was customary to shoot it out of the tree with a gun.
Christmas holly belongs to the genus Ilex, which consists of more than 400 species, ranging from a 6-inch dwarf to a 70-foot tree. Depending on the species, holly berries may be red, orange, yellow or even black.
But the holly that says "Christmas" is most likely to be English holly (Ilex aquifolium) or American holly (I.opaca). The red berries and evergreen leaves with unmistakable spiny scalloped edges are emblematic of the holiday season.
Holly bears insignificant white cup-shaped flowers in spring and early summer. The plants are dioecious, meaning that they have either male or female flowers and only the female plant bears fruit. For best results, a male and female should be planted within 30 to 40 feet of each other. Newly planted holly may not bloom for several years, so be sure to purchase your plant from a reputable nursery that can assure you of its gender.
Hollies grow best in full sun and prefer moist well-drained soil. They will tolerate shade but will not grow to their full potential. Holly's natural growing habit is an attractive pyramidal shape, making it an ideal year round focal point in the garden.
Holly can be pruned during December, and the cuttings can be enjoyed throughout the holiday season. Holly leaves tend to drop if they are brought indoors, so it is best to use the cuttings outdoors. If holly is overgrown, some experts now recommend the "hat rack" method of pruning. This technique is considered inappropriate for pruning most trees but is a successful method used to rejuvenate holly. In late winter, cut the branches back by one-half to three- fourths. The result will indeed resemble a hat rackand will be a complete eyesore, but the plant will rebound fully in two to three years. Although reduced in size, the foliage will be far more abundant.
While no plant is completely deer-resistant, American holly and the Morris hollies named for John T. and Lydia Morris, donors of the Morris Arboretum in Philadelphia, are generally not browsed by deer.
As the lyrics for the famous Frank Sinatra song remind us, "It's time for mistletoe and holly!" Enjoy these two classic holiday plants during this festive season.
Kate DeSimone is a Penn State Master Gardener. Columns by master gardeners will sometimes appear in place of the Garden Q&A by Sandy Feather, a Penn State Extension educator.