Pucker Up, It's Christmas

The romantic, parasitic, poisonous Mistletoe

Romantic, parasitic and poisonous is how the Woodland Trust describes the common mistletoe.  But the tradition of hanging mistletoe at Christmastime has a long history, many details of which are lost in the mists of time.  And some aspects of which are, well, x-rated.

Viscum album, the European mistletoe, growing on aspen, Populus tremula, in Cambridge, England. PHOTO: by Andrew Dunn, 26 December, 2004. CC BY-SA 2.0

What, exactly, is mistletoe?  The common name refers to hundreds of species of parasitic, or semi-parasitic, plants that grow on the branches of trees and shrubs.  Some mistletoe lineages are more or less closely related, while others are unrelated but have evolved similar habits and appearances.

We will focus specifically on Viscum album, the European or common mistletoe, that has an especially long and storied cultural history.  But first, a little about the plant itself.

It was given its scientific name by Linnaeus in the 18th century, but was well-known to Europeans since antiquity.  It can parasitize any of about two hundred species of host trees and shrubs, and belongs to the sandalwood family, Santalaceae.  Among the one thousand species of sandalwoods are trees, shrubs, herbs, climbers and, of course, the tree-top parasites we hang in our homes.  Parasitism is not unique to mistletoes in the family, with other sandalwoods using specialized roots to tap into the roots of nearby trees and steal nutrients. Molecular studies have determined that mistletoes evolved five times within the Santalales, to which the sandalwoods belong.  First about 80 million years ago, and most recently about 28 million years ago.

Viscum album is small, semi-parasitic, and evergreen.  Its described as semi-parasitic because it attaches with and uses a structure called an haustorium to penetrate the host plant and extract nutrients and water, and, at the same time, remains capable of photosynthesis.  It grows as a spherical ball up to one meter in diameter, high in the branches of trees.  Its evergreen leaves are oval, smooth along the edge, and situated in pairs along a woody stem.  It produces clusters of three to five small flowers, each with four petals.  Male and female flowers are produced on separate plants.  Two to six white, waxy berries are produced in clusters. Its leaves, stems, and berries are all quite poisonous, so of course we use it in holiday celebrations.  The substance tyramine found in the European mistletoe can cause blurred vision, nausea, vomiting and diarrhea — so let the festivities begin.

If you are a mistletoe with your talons inserted into a branch, how do you get your offspring high into some other tree?  This is where the plot thickens, along with the pulp around mistletoe seeds.  Even though most birds are attracted to colorful winter berries, there are avian allies in seed dispersal, such as the mistle thrush, redwings, and fieldfares, that eat its white berries and spread its progeny.  The seeds in the berries are coated with a very sticky substance that adheres to whatever it touches.  Stuck to its beak, birds will rub the seeds off on branches.  And even those eaten by the bird remain sticky in their droppings, thereby sometimes ending up in a tree rather than on the ground.  As this gooey pulp hardens, it securely glues the seed in place.  When it’s the right place, roots grow and penetrate the bark of a host tree.

The white berries and sticky pulp are where the x-rated part of our story begins, so it’s time for a short musical interlude while you send the kids out of the room.

[Imagine a short bit of elevator music here] 

The substance coating mistletoe seeds is sticky, like semen — and I don’t mean sailors on a ship — a fact that was not overlooked by ancient societies.  This bit of naughty accounts, in part, for the fascination with this parasite.

All kinds of special properties have been ascribed to the mistletoe.  Pliny the Elder tells us that the Romans prescribed it as a treatment for epilepsy and ulcers.  Romans also hung mistletoe over doorways associating it with love and understanding, and negotiated the end of warfare under a sprig that was seen as a symbol of peace.  Greeks thought it useful for spleen disorders and menstrual cramps.  And, mistletoe was thought to grant heroes passage to the underworld.  For Druids, it offered protection against evil. And early Christians depended on it to ward off witches and demons, sort of the Ring video doorbell of their age.

Pagans saw a resemblance of the gooey seeds to semen, accepting this as a sign of devine male essence and thus revering white berries as symbols of male fertility.  Celts thought mistletoe to be the semen of the god of thunder, Taranis, and ancient Greeks actually called it oak sperm.  Through the Middle Ages, it remained associated with fertility and vitality, the latter reinforced by its evergreen presence through the cold, dark, barren winter.  The exact steps from Pagan semen potency to kissing under the mistletoe are not known, but one can blush a little, make inferences, and fill in the blanks.  With all this talk of male essence, parents of the Mistletoe Queen, crowned in Tenbury Wells each year, must be so proud.

The kissing tradition may have originated in Greece from a connection of its fertility symbolism and inclusion in the Saturnalia festival and wedding ceremonies.  But modern popularity can be traced to servants in England, from whom it later spread to the middle classes.  One version of the tradition, described by Washington Irving, says that young men are granted the privilege of kissing girls under the mistletoe, plucking a berry after each kiss, until they are gone — along with the privilege.  Conveniently, it was said to be bad luck for a girl to decline to be kissed on the cheek.

When you hear Jimmy Boyd belting out “I saw mommy kissing Santa Claus,” or find yourself, eyes closed and puckered up in a doorway, you may wish to momentarily push the origins of the mistletoe tradition out of mind.  As for me, I’m glad to be in the U.S. where we use Phoradendron leucarpum, instead.  Its red berries are not so suggestive.

Further Reading

Anon. (2015) In pictures: the history of mistletoe.  The Telegraph, 16 December.

Dunn, Rob (2011) Mistletoe: The evolution of a Christmas tradition. Smithsonian Magazine, 21 December.

Vidal-Russell, R. and D. L. Nickrent (2008) The first mistletoes: Origins of aerial parasitism in Santalalaes.  Molecular Phylogenetics and Evolution 47: 523-537.