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Consumer Horticulture

Department of Horticulture and Landscape Architecture

Mistletoe (Phoradendron leucarpum)

By Mary Welch-Keesey, Purdue University Consumer Horticulture Specialist, and Martha Bailey, volunteer, at White River Gardens

Mistletoe is the common name for shrubs in the Viscaceae family, most of which are parasitic. The ancients considered the plants to be mystical because mistletoe would suddenly appear in trees and did not have roots. They did not realize that fruit-eating birds distributed mistletoe seed by rubbing their beaks against the trees and via their droppings. The plant was considered sacred in pre-Christian Europe. It was variously credited with curing diseases, rendering poisons harmless, and protecting the house from ghosts. It became associated with the Christmas season because the Druids were said to welcome the new year with branches of mistletoe. Over the centuries the berries have had medicinal uses; the Native Americans used the shrub long before the Europeans arrived in America. However, THE BERRIES ARE TOXIC IF THEY ARE EATEN.

American mistletoe (Phoradendron leucarpum) and English mistletoe (Viscum album) are similar in appearance. The American generic name is based on the Greek Phor meaning "thief" and dendron meaning "tree" because it steals the life juices from the host tree. The English generic name refers to its sticky white berries. The American mistletoe is the plant which is available in North American holiday markets.

Mistletoe forms a drooping yellowish evergreen bush about 2-3 feet long on the branch of a host tree. It has thickly crowded, forking branches with oval to lance-shaped leathery leaves about 2 inches long, arranged in pairs, each opposite the other on the branch. The flowers, in compact spikes, are bisexual, unisexual, or regular. They are yellower than the leaves and appear in the late winter; they soon give rise to one-seeded, white berries, which when ripe are filled with a sticky, semi-transparent pulp.

After germination a modified root penetrates the bark of the host tree and forms a connection through which water and nutrients pass from host to parasite. Mistletoes contain chlorophyll and can make some of their own food. Species in America parasitize many deciduous trees, including oaks. Mistletoes are slow-growing but persistent; their natural death is determined by the death of the hosts. They are pests of many ornamental, timber, and crop trees. The only effective control measure is complete removal of the parasite from the host.

One custom which the English and Americans share is that of kissing under the mistletoe, a practice that originated in England in the 19th Century. Since the berries are toxic, it is wise, when bringing a spray into the house, to hang the plant high enough that children cannot reach it. BERRIES OF ALL MISTLETOES CONTAIN TOXIC COMPOUNDS THAT ARE POISONOUS TO ANIMALS AND HUMANS. Often, plastic berries are substituted for real ones to prevent poisoning and increase shelf life.


Last updated: 6 April, 2006
For questions on this article, please contact Mary Welch-Keesey (mwelch@indyzoo.com).
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