From bird droppings to holiday kisses: How we ended up under the mistletoe

Stealing a smooch under the mistletoe is a time-honored holiday tradition — but the word itself has an origin that invokes the exact opposite of romance.

As part of NPR’s “Word of the Week” series, we’re exploring the history of the plant’s name, diving into the tradition of kissing beneath it, and taking a scientific detour along the way.

The etymology of mistletoe — a plant with small, oval evergreen leaves and waxy white berries — likely comes from the Anglo-Saxon words for manure — “mist” or “mistel” — and “tan” (sometimes rendered as “toe”), meaning “twig” or “stick.”

“It literally means bird poop on a twig,” according to Susie Dent, a British lexicographer and author of Guilt by Definition.

The name stems from the way its seeds are carried by birds and dropped after passing through their digestive tract. This method of seed dispersal is called endozoochory, says Tristram Seidler, a biology professor at the University of Massachusetts Amherst and the curator of the UMass Amherst Herbarium.

In short, animals eat fruits, including berries, move on and “deposit” the seeds in a different location, he says. For mistletoe seeds, that location happens to be the tops of trees. From an evolutionary standpoint, Seidler says, species survival can depend on getting seeds away from the parent plant.

“Any seeds that land near their parent plant may germinate,” he explains. “But they’re almost certainly going to be wiped out by disease because those areas tend to be crowded and small plants are very susceptible to their own pathogens.”

Humans, then, make use of the mistletoe spread by those birds — planting it in cultural practices that stretch back into antiquity.

The oldest customs surrounding mistletoe are likely tied to celebrations of the winter solstice, according to Bettina Arnold, a professor of anthropology at the University of Wisconsin–Milwaukee. These go back to the Neolithic era in prehistoric Europe.

“All agricultural societies would have made note of [the winter solstice] because it literally is the time when… you can start seeing the days getting longer again,” she says. “So it’s a return to life after sort of a seasonal death, in a way.” The mistletoe, being evergreen, “is actually almost a metaphor for that.”

Arnold says that Pliny the Elder, a first-century Roman author, provided a detailed account of mistletoe and its use by druids, a nature- and ritual-focused priesthood that lived in Iron Age Gaul (modern-day France) and the British Isles. Pliny said that when they found mistletoe growing on a particular kind of oak tree, a priest in white vestments would climb up to cut down the mistletoe with a golden sickle.

“They believe that mistletoe given in drink will impart fertility to any animal that is barren, and that it is an antidote for all poisons,” Pliny wrote. (In fact, modern medical literature says the exact opposite).

Given mistletoe’s association with fertility and rebirth, it’s not surprising that it made its way into Christian tradition, Arnold says, noting that although we often forget it today, “the Roman Catholic Church is really kind of an extension of the Roman Empire.” The Romans themselves also had their own solstice tradition that seeped into Christian practice: Saturnalia, in honor of the sun god, Saturn, included decorating homes with evergreen boughs, wreaths and garlands to symbolize renewal.

Norse mythology adds another mistletoe tale — of Baldur, the god of light. In a story reminiscent of the Greek hero Achilles, Baldur’s mother, Frigg, makes her son invincible to all things except mistletoe. Loki, the trickster, exploits this unusual weakness by using an arrow made of mistletoe to kill Baldur. In some later versions of the story, Frigg’s tears over her son’s death become mistletoe berries, symbolizing her love.

So, what about all the kissing?

A reference appears in a song from the 1784 musical comedy Two for One, which celebrates “what good luck has sent ye/ And kiss beneath the mistletoe.” It’s the oldest written reference to the custom, according to Arnold. It appears to have gained popularity in the following centuries, with holiday themes of regeneration, renewal and redemption helping to reinforce it.

According to author Dent, the story of mistletoe reflects this transformation, evolving from a “slightly scatological beginning … [to] blossom into something rather beautiful.”