In some parts of England the Christmas mistletoe is burned on the twelfth night lest all the boys and girls who have kissed under it never marry. It is most abundant on apple trees, poplars, willows, lindens, and hawthorns. The scientific name of the mistletoe family is Loranthaceae, which consists of about 20 genera. Some people have sentimental whims about the myths of mistletoe, but this evergreen, parasitic plant is a common pest that reduces the vigor and even threatens the survival of many shade trees. Another species of broadleaf mistletoe in California, P. villosum, infests only oaks.
Leafy mistletoes have green stems with thick leaves that are nearly oval in shape.
Plants often develop a roundish form up to 2 feet or more in diameter. The small, sticky, whitish berries are produced from October to December. Evergreen clumps of mistletoe are readily observed on decidous trees in winter when leaves are off the trees. The birds feed on and digest the pulp of the berries, excreting the living seeds that stick tightly to any branches on which they land. In most cases, the initial infestation occurs on larger or older trees because birds prefer to perch in the tops of taller trees.