It is Yuletide Plants Week on The Quantum Biologist! This week, we’ll take a closer look at three plants that make the Christmas season special — both the fascinating social histories of them, and the biology behind the myth.
Christmas has its cultural traditions, and its private ones. I’m sure your family has its own peculiar private traditions. Perhaps your Uncle Frank hits the eggnog too hard and reenacts the Siege of Khe Sanh in the living room every year. Or maybe you annually try to recreate Frank Lloyd Wright’s “Falling Water” in gingerbread. If you hew closely to old cultural traditions, you might tack up a sprig of mistletoe. But since you probably don’t, you are then a potential victim of one of my personal private traditions, which is ranting to anyone who will listen about what a shame it is that mistletoe isn’t a cultural tradition anymore.
It must have been phased out so gradually that few noticed its disappearance. But somehow, mistletoe has gone the way of sugar plums and other grand old British Christmas traditions that now exist mainly in carols and poems, perennially perplexing small children. (I still don’t know what “figgy pudding” is. I just know I want some.) Perhaps mistletoe was used once too often by sad, goofy bachelors at holiday parties, a sprig of it dangling from a hat like a an anglerfish’s unlucky lure. Perhaps it fell prey to our cultural ignorance and mistrust of wild plants; nevermind how many deadly poisons we willingly invite under our sinks, mistletoe has the reputation as the thing that can kill your dog. Or maybe, despite the Free Love revolution of the ’60s and ’70s, we’ve actually become more prudish about kissing strangers. Whatever the reason, the decline of mistletoe, to me, speaks volumes about its dangerous power. Like an ancient god of Love and Thunder, its deadly and erotic potential is simply too overwhelming for today’s passive society, and its shrines have been abandoned in the woods. Let’s examine how the mistletoe tradition started, and how the biology of the plant created the legend surrounding it.
Mistletoe is a hemi-parasite: It has green leaves for photosynthesis, but is also completely dependent on the tree branches it lives on for nutrients, water, and sugar. In profusion, mistletoe can kill a tree, but it rarely reaches that abundance on any one host. There are many species of mistletoe and unrelated dwarf mistletoe, which colonize hundreds of species of trees. Here in New Mexico, for example, we have one broadleaf species (Phoradendron tomentosum) which grows on cottonwoods, and another true, leafless mistletoe (P. juniperinum) that is exclusive to juniper. You might think that its parasitic nature makes it a plant pathogen and a worthless vampire, but in fact, mistletoe is considered a keystone species, serving both its hosts and the larger ecosystem far beyond what its small stature would suggest. That’s because both the young shoots and the mature berries, though toxic to mammals, are an important food source for songbirds, whether it’s the thrushes and cardinals of New England or the phainopeplas and piñon jays of the Sonoran desert. (In fact, there is even a species which grows exclusively on cacti.) A study of Juniper Mistletoe found that, despite slowing the trees’ growth, the parasite actually aids its hosts by attracting birds to the junipers even when juniper berries are so scarce as to be beneath the birds’ notice. In other words, the birds come for the mistletoe berries, stay for the juniper berries, and spread both. Junipers with mistletoe attract three times as many birds as those without, giving them a reproductive advantage. In this way, mistletoe’s powers of attraction complete the forest.
But in England, the prototypical Christmas mistletoe Viscum album grows primarily on oaks. And here I pause to throw my own grenade into the hyped-up, so-called “War on Christmas:” There are many who petulantly whine about Christ being the “Reason for the Season,” to which I can confidently say, “Bah and Humbug.” Christmas’ pagan roots in the celebration of the Solstice are evident in the origin of mistletoe as a religious tradition. The Druids of Albion worshipped trees as demi-gods, and considered the mighty oak the most sacred of their pantheon. Mistletoe, a plant that grows on oaks with roots that never touch the Earth, was thought to contain a piece of the holy oak tree’s soul. It must have mystified those tree-huggers of old, how the plant seemed to thrive despite suckling on a spiritual lightning rod, remaining green and alive in a season of death. So five days after the first full moon of the Winter Solstice, the Druid priests would ascend a local oak to harvest mistletoe for their shamanic rituals. Only a golden sickle could be used to cut the plant, while priests stood below to catch it in a tarp so that it never touched the ground. Sprigs were distributed to the villagers and placed above doors to ward off faeries, evil spirits, and all manner of bad luck. It was used in male fertility rites, possibly because the waxy white berries resemble drops of semen. And if two warring parties happened to meet in the forest under a tree bearing mistletoe, they had to lay down arms for the rest of the day. Hence, the first “kiss” under the mistletoe.
The vikings of Scandinavia had their own mistletoe traditions. In Norse myth, the God of Love Balder was so much doted on by his mother Frigga that she made every creature and element promise to never harm him. But the jealous trickster god Loki found the one thing in existence that had not been forced to swear the oath: the homely, seemingly harmless mistletoe. He fashioned an arrow from its wood, and offered Balder’s blind brother Hoder a free archery lesson. Guiding the mistletoe missile in Hoder’s sightless aim, Loki used the poor dupe to shoot and kill Balder. Upon hearing the news, Frigga’s tears fell and became the white mistletoe berries, and she cursed the plant to become the scraggly parasite it is today. In the happy version of the story, Balder is restored to life, and Frigga reverses the curse, making mistletoe a symbol of love.
Because of its pagan associations, mistletoe was banned from early churches. In fact, Christians stole the Balder story and re-appropriated it; in their version, mistletoe was once a tree whose wood had been used to make the cross of the Crucifixion. As punishment, the mistletoe was shrunk to its present size, and considered a symbol of the Devil. But eventually, and as always, the pagan tradition won out in an adulterated form, and mistletoe was hung above doorways again. However, its power was limited: every time you kissed a girl under the mistletoe, you removed a berry. When the berries were gone, so was the plant’s erotic power.
I believe it is time to restore that power. This year, find the mistletoe growing in a green cloud in a tree near you, and make it part of your Christmas traditions again. Mistletoe has long hung above the punch bowls of history as a reminder of the real Reason for the Season: Warding off gnomes and ensuring fertility for the coming year’s livestock. And smooching. Let’s not forget the smooching. There is no reason that Christmas need be a completely sexless holiday. Christmas is the child of two parents: the Christians, for whom it is a celebration of life through celibacy, and the Druids, who worshipped a plant whose berries looked like semen. We attend Mass, build creches in the front yard, and participate in Nativity pageants. Then we go home, get sloshed on hot toddies, revel in wild-abandoned gluttony, and have really awkward moments with “platonic” friends under the mistletoe. But from awkwardness springs Love, and Love is like mistletoe: A life-giving parasite. It brings the songbirds to the heart of a barren forest. It steels the heart against the evils of a long winter with green hope. It’s slightly toxic. It relies entirely on the strength of greater and older gods. And while it is still sacred, it never touches the ground.