How mistletoe became an icon of Christmas

Mistletoe is undoubtedly an icon of Christmas.  It’s that little plant hanging harmlessly over a doorway that encourages couples everywhere to kiss underneath it.  According to Live Science, the kissing tradition goes way back, back to a time before Christmas even existed in fact.  

The tradition comes from ancient Greece where mistletoe was associated with fertility.  Kissing under mistletoe is said to go bag to the pagan festival of Saturnalia, a festival honoring the god Saturn.  The festival was originally held on December 17 but later expanded with festivities running until December 23.  A sacrifice to Saturn was followed by a banquet and a tradition of gift giving; sounds familiar, right?  In Rome, treaties between warring parties were signed under mistletoe, associating the plant with peace.

The Spruce reports another origin of the kissing under mistletoe tradition.  Norse mythology has a place for mistletoe but some of it is decidedly darker than the Saturnalia in Greece.  According to one myth, the death of Baldur, a beloved son, was presaged to his father Odin in a dream.  In fear the gods made all sorts of physical objects, trees, rocks, water, promise not to hurt Baldur. Mistletoe, being a small and inconspicuous plant, was overlooked.  

When the gods thought that Baldur was safe, they celebrated by throwing things at him and laughing as they harmlessly leaped away.  During this festive atmosphere, Loki crept up to Hodr, the blind god with a dart he’d made out of mistletoe, offering it to Hodr to throw at Baldur.  When Hodr threw the dart as part of the celebration, Baldur was killed. After a failed attempt to bring Baldur back from the dead, it was agreed that any passing under mistletoe would exchange a kiss in memory of the dead god.  More interesting perhaps than the origins of the kissing tradition, though, is the plant mistletoe itself.

According to National Wildlife Federation, there are actually many plants that can be called ‘mistletoe’.  Worldwide, there are as many as 1,300 mistletoe species. According to Britannica, all mistletoe species come from three plant families, Loranthaceae, Misodendraceae, and Santalaceae but especially from three genera in the Santalaceae family.  The contiguous US and Canada together are home to 30 species of mistletoe. The name mistletoe comes from ancient Anglo-Saxons, the word ‘mistel’ means ‘dung’ while the word ‘tan’ (later changed to ‘toe’) means ‘twig’.  Dung twig may seem like an odd name for a plant, but it makes a lot of sense if you know a bit about the life history of mistletoe.

Despite its association with Christmas and smooching, there’s no way around a dark truth, mistletoe is a parasite.  Mistletoe can be found growing on trees throughout the world. The mistletoe I’m most familiar with is a green scaly thing that’s easy to miss on a juniper tree in the high desert of the Colorado Plateau.  In context, this mistletoe actually looks like an overgrown clump of the plant’s own foliage at first glance, perhaps a sign of cancer in the tree.

When the mistletoe grows berries, it becomes a bit more obvious.  The white berries of mistletoe attract birds which apparently find them tasty.  The seeds hidden in the berries hold a secret that allows mistletoe to disperse to the limbs of other trees so effectively.  

Mistletoe seeds are sticky.  Sometimes a bird gets a seed stuck to its beak and wipes a seed off onto a tree branch where it sticks, reading to grow its roots into the tree and parasitize it.  Other times, the seed passes through the bird’s digestive tract and sticks to the tail feathers of the bird. When this happens, the bird usually wipes the lucky seed off onto a branch, or twig.  This is why ‘dung-twig’ is actually a pretty good name for mistletoe. An atypical mistletoe, the Dwarf Mistletoe, actually shoots its seeds away, hopefully towards another host plant using water pressure.  The life of mistletoe is largely determined by how good of a host plant it’s rooted to.

Mistletoe sends its roots directly into the host plant, sucking away water and nutrients.  An infestation of mistletoe can eventually kill a host plant. Mistletoe does have chlorophyll, so it makes some of its own food, not taking a completely free ride from its host plant but when that host plant dies, so does the mistletoe, not able to pull entirely its own weight.  Not everything about the life of mistletoe is bleak; it provides life as well as takes it.

Many birds nest directly in mistletoe, and according to National Wildlife Federation, 43% of Spotted Owl nests in a single forest were associated with mistletoe.  64% of Cooper’s Hawk nests in northeastern Oregon were in mistletoe. Squirrels sometimes nest in mistletoe also.  Three species of butterfly depend on mistletoe, their caterpillars feeding on the plant exclusively.

According to the Xerces Society, the Johnson Hairstreak butterfly’s caterpillar is perfectly camouflaged in the foliage of Dwarf Mistletoe where it lives in the Pacific Northwest.  Butterflies and native bees also feed on the nectar of mistletoe. The Australian National Botanical Gardens reports that in Australia and Africa, there are entire genera of butterflies that feed almost exclusively on mistletoe.  

Australia’s also home to an interesting bird, the Mistletoebird; Bird Life Australia shows the male bird as a small bird with black plumage and a bright red throat and grey belly.  The female birds are a lighter grey color with no red. The bird lacks the gizzard many birds have, instead having a simpler digestion system adapted to easy to eat mistletoe berries, the sticky seeds of which it spreads to branches.  The bird sometimes also catches insects and eats other plants but it’s pretty dependent on mistletoe as a staple. Interestingly it’s not just the Mistletoe bird or a few butterflies that benefit from the plant.

A study published in 2002 carried out in New South Wales Australia showed some ecological benefit to mistletoe.  A survey of birds in woodlands was carried out at the start of the study and species numbers carefully recorded.  Mistletoe was then removed from a portion of the woodlands being studied and the area re-surveyed as well as another area with mistletoe intact.  Interestingly, the area with mistletoe showed a greater number of bird species than the area without mistletoe. 52 bird species were found in the area denuded of mistletoe while 61 species were found in the area with mistletoe.

It’s not clear exactly why more birds would be found near mistletoe, perhaps it’s because of greater numbers of insects feeding on the plant.  Whatever the reason, maybe the ancient Greeks were onto something when they associated a simple parasitic plant with fecundity.

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By Zach Fitzner, Earth.com Contributing Writer