But how did the festive Christmas tradition of kissing under mistletoe come about?

The long-lived custom intertwines the mythology and biology of this intriguing plant.

There are more than 1,000 species of mistletoe, which grows the world over.

In fact, the ancient Europeans were so captivated by the plant's unusual growth habits that they included it in their legends and myths.

In ancient Rome, Pliny the Elder described how the Druid priesthood in ancient England believed that mistletoe was a plant dropped down from heaven by the gods.

That explained its unlikely position amongst the high branches of certain trees.

They also believed it had powers of healing and bestowing fertility.

Meanwhile, Scandinavian legend told of the plant's mystical qualities in the story of the god Baldr and his adoring mother Frigg, goddess of love, marriage, and fertility.

Frigg loved her son so much that she commanded every plant, animal, and inanimate object to vow they'd never harm him.

In her fervor, however, she overlooked the mistletoe.

The mischievous god Loki realized this oversight and pierced Baldr's heart with an arrow carved from a mistletoe branch.

Frigg cried tears of such sadness that they formed the mistletoe's pearly berries, making the other gods pity her and agree to resurrect Baldr.

Hearing the news, Frigg became so overjoyed that she transformed the mistletoe from a symbol of death into one of peace and love.

She mandated a one-day truce for all fights, and that everyone embrace beneath its branches when they passed to spread more love into the world.

In the 17th century, British colonists arriving in the New World found a different, but very similar looking, species of mistletoe.

They applied it to these tales of magic, fertility, and love, spreading the mistletoe-hanging tradition from Europe into America.

By the 18th century, people in Britain had turned this into a Christmas tradition, but this custom comes down to more than just human imagination.

All of it was inspired by the plant's intriguing biology.

We see mistletoe as a festive decoration, but draped on tree boughs in the wild, it's known as a partly parasitic plant.

Mistletoe relies on modified roots called haustoria that penetrate the tree bark and siphon off the water and minerals trees carry up their trunks.

To colonize nearby trees with its seeds, mistletoe depends on birds and other creatures to do the dispersing.

Birds that eat the mistletoe's sticky white berries sometimes get rid of the gluey seeds by wiping them off onto tree bark.

Or with a bit of luck, they excrete the indigestible seed onto a tree where it germinates and starts to grow.

With its resilience and foliage that stays lush, even while the surrounding trees lose their leaves, you can see why mistletoe captivated our superstitious ancestors.

They saw these as signs of the plant's magical qualities and fertility.

Even today, the mistletoe inspires wonder with the diversity of wildlife it supports.

More than just a parasite, it's also known as a keystone species.

It's eaten by a diversity of animals, including deer, elk, squirrels, chipmunks, porcupines, robins, bluebirds, mourning doves, and the butterfly genus, Delias.

Some mistletoe species produce dense bushes, which are excellent nesting locations for a variety of birds.

And despite their parasitic relationship with trees, mistletoes can also help other plants.

For instance, juniper sprouts near mistletoe to benefit from the visiting berry-eating birds.

Through the many benefits it provides, mistletoe influences diversity, and allows ecosystems to flourish.

You might even say that for this iconic plant, life imitates legend.

In the wild, mistletoe has the power to bring things together, and in our own traditions, we see that happening, too.