John Hartman, Plant Pathology Professor Universtiy of Kentucky
Once autumn leaves have fallen, mistletoe becomes highly visible on large trees throughout Kentucky. Phoradendron, the scientific name for this parasitic plant, means tree thief. You can commonly find these small leafy plants on twigs and branches of many hardwood species in the southern two-thirds of the United States. Mistletoes extract water, mineral elements and food from their host tree by way of a parasite nutrient-uptake organ; hence the name, tree thief.
Mistletoes’ use in holiday traditions has roots in pagan times. Its parasitic nature and the fact that it appears to be alive while the host tree appears dead, led some to believe mistletoe mysteriously held the life of the tree during winter. Druids harvested mistletoe in a special rite, never letting the plant touch the ground, then hung it in their homes for good luck.
Our modern-day mistletoe holiday tradition likely originates with a mythological Norse goddess of love and beauty. Frigga, whose son was restored from possible death by mistletoe, was thought to bestow a kiss on anyone walking beneath one. Today, when two people meet under the mistletoe, tradition suggests they must exchange a kiss for good luck.
Phoradendron, the most common mistletoe growing in Kentucky, resembles another species that grows in Europe. It has simple, fleshy green leaves arranged oppositely on the stem. Stems are short and more branched than the host tree, so mistletoe often appears as a spherical bunch of dense vegetation. These bunches may be a foot or two in diameter and are located high in the tree for better sunlight exposure. Mistletoe berries range from white to straw-colored to light red. Birds eat the fruits, reportedly toxic to human and animals, then deposit the seeds onto branches where they germinate and penetrate the host tree. Since birds tend to roost in open-grown trees, mistletoes do not appear as frequently in forest trees. Generally, they do not cause much damage, although they can be harmful to a tree already under stress. If mistletoe appears on landscape trees or other trees in the urban forest, you can control it through pruning.
