From very early times plants, animals, and even minerals have played an important part in the expression of religious ideas and in the execution of religious rites. Among the plants, sacred, and closely allied to the mystic life of a portion of the human race, there is none more interesting and rich in legend than the mistletoe. This was associated with religious observances before the time of Christ and was mentioned by our earliest historians. There are over seventy species of this peculiar plant. Both the American variety (_Phoradendron flavescens_) and the European, or true mistletoe (_Viscum album_), belong to a family of parasites, so called because they derive their nourishment entirely or in part from some other plant instead of taking it directly from the soil. Owing to the presence of the green coloring matter (_Chlorophyll_), in the stems and leaves, the mistletoe is not entirely parasitic, but is to a certain extent self-supporting, drawing but a portion of its nourishment from the tree on which it grows. It is found both on deciduous and on evergreen trees. In some locations in Europe it is especially abundant on the apple tree and, if in the right climate, there are few tree species which are exempt from serving as its host. The mistletoe is an evergreen shrubby plant of slow growth, attaining a length of about four feet and its duration of life is practically that of the tree on which it grows. The leathery leaves and rugged stems are yellowish green in color and, in the axils of the leaves, are the small and insignificant flowers, which ripen about Christmas-tide into pearly white translucent berries. The seeds are probably distributed through the agency of fruit-eating birds which, after eating, wipe their beaks on the trunks and limbs of trees, leaving the seeds snugly planted in the crevices of the bark. In Scandinavian mythology we find the mistletoe used to cause the death of one of the favorite gods of the Norsemen, Baldur, the god typifying the beautiful, the good, and the wise. In this myth other friendly gods, fearing Baldur's death, with his mother, exacted an oath from animals, plants and minerals that they would not injure him. Unfortunately, however, the mistletoe was forgotten and Loki, the god of evil, knowing this fact and jealous of Baldur's beauty, gathered a branch, and taking it to Hödur, the blind god of brute strength, directed him how to aim it. Baldur was pierced by the mistletoe and fell to the ground, dead.