How the Tradition of Kissing Under Mistletoe Started

Doorway mistletoe

The Spruce / Margot Cavin 

While kissing under the mistletoe is a long-standing Christmas tradition, few realize how the tradition started, or that the plant grows on a tree and has earned the classification as a parasitic shrub.

Its literary history is just as nuanced—as Washington Irving wrote in "Christmas Eve," "The mistletoe is still hung up in farm-houses and kitchens at Christmas, and the young men have the privilege of kissing the girls under it, plucking each time a berry from the bush. When the berries are all plucked the privilege ceases." Seems like we've all forgotten the part about plucking the berries (which, incidentally, are poisonous), and then refraining from kissing under the mistletoe when the berries run out.

Along with holly, laurel, rosemary, yews, boxwood bushes, and, of course, the Christmas tree, mistletoe is an evergreen displayed during the holiday season. But, when the Christmas decorations come down, mistletoe fades from our minds for another year. Here, we're diving deep into the tradition and lore behind mistletoe.

Botanical Information on Mistletoe

The unusual botanical history of mistletoe goes a long way towards explaining the awe in which it was held by ancient peoples. In spite of not being rooted in soil, mistletoe remains green throughout the winter, while the trees upon which it grows and feeds do not (European mistletoe often grows on apple trees; more rarely on oaks).

Most types of mistletoe are classified as partial parasites—they are not full parasites since the plants are capable of photosynthesis. But mistletoe plants are parasitic in the sense that they send a special kind of root system (called "haustoria") down into their hosts in order to extract nutrients from the trees, allowing them to stay alive throughout the year while their "host" plant does not, and lending them an almost-mythical quality.

Mistletoe is in the Loranthaceae family, though various types of mistletoe grow all over the world so it's difficult to generalize too much about the plant. For example, the flowers of tropical mistletoes can be much larger and more colorful than the small yellow flowers (later yielding whitish-yellow berries) that Westerners associate with the plant. The mistletoe common in Europe is classified as Viscum album, while its American counterpart is Phoradendron flavescens.

Origins of the Word 'Mistletoe'

The origin of the word "mistletoe" is every bit as complex and obscure as the botany and myth surrounding the plant. The name originated from the perception in pre-scientific Europe that mistletoe plants burst forth, as if by magic, from the excrement of the "mistel" (or "missel") thrush. According to Sara Williams at the University of Saskatchewan Extension, "mistel" is the Anglo-Saxon word for dung, while "tan" is the word for twig—so the name mistletoe literally means "dung-on-a-twig." Belief in mistletoe's spontaneous generation has long been discredited—in fact, the plant is spread by seeds as they pass through birds' digestive tracts.

Norse Myths and the Mistletoe Tradition

As it turns out, a custom that developed in Norway led to our modern-day mistletoe tradition. According to anthropologists, the Norse myth dictated that if, while out in the woods, you happened to find yourself standing under a mistletoe upon encountering a foe, you both had to lay down your arms until the following day.

This ancient custom went hand-in-hand with the Norse myth about Baldur, son of the god Odin and his wife, the goddess Frigga, found in the Prose Edda. When Baldur was born, Frigga made every plant, animal, and inanimate object promise not to harm Baldur. However, Frigga overlooked the mistletoe plant, and the mischievous god of the Norse myths, Loki, took advantage of this oversight. Loki tricked one of the other gods into killing Baldur with a spear made from mistletoe. Hermódr the Bold was appointed to ride to Hel in an attempt to bring Baldur back. Hel's condition for returning Baldur was that absolutely every last thing in the world, living and dead, had to weep for Baldur. Failing that, he would remain with Hel. When this condition was put to the test, all wept except for a certain giantess, believed to be Loki in disguise. Baldur's resurrection was thus thwarted.

Variations on this myth about Baldur and the mistletoe have made their way down to us. For example, some relate it was agreed, after the death of Baldur, that from then on mistletoe would bring love rather than death into the world, and that any two people passing under mistletoe would exchange a kiss in memory of Baldur. Others add that the tears Frigga shed over the slain Baldur became the mistletoe berries.

Mistletoe's Famous Literary Past

As might be expected from a plant that has held people's fascination for so long, mistletoe has also carved out a niche of fame for itself in the world of literature. In Virgil's "Aeneid," the most famous book in classical Latin literature, the Roman hero Aeneas makes use of this "golden bough" at a critical juncture of the book. Found on a special tree in the grove sacred to Diana at Nemi, the prophetess Sibyl instructed Aeneas to pluck this magic bough before attempting his descent into the underworld. Sibyl knew that, with the aid of such magic, Aeneas would be able to undertake the perilous venture with confidence. Two doves guided Aeneas to the grove and landed on the tree:

...from which shone a flickering gleam of gold. As in the woods in the cold winter the mistletoe—which puts out seed foreign to its tree—stays green with fresh leaves and twines its yellow fruit about the boles; so the leafy gold seemed upon the shady oak, so this gold rustled in the gentle breeze. ("Aeneid" VI, 204-209).

Similarly, the title of Sir James G. Frazer's anthropological classic, "The Golden Bough," references this very scene in Virgil's Aeneid—but just how can something green like mistletoe become associated with the color gold? According to Frazer, mistletoe could become a "golden bough" because when the plant dies and withers it acquires a golden hue.

Botany and folklore most likely must be mingled to arrive at the full explanation. The perception of goldenness in the dried leaves of mistletoe plants was probably influenced by the fact that, in the folklore of Europe, it was thought that mistletoe plants are brought to earth when lightning strikes a tree in a blaze of gold. A fitting arrival that would be, after all, for a plant whose home is halfway between the heavens and the earth.