You're most likely familiar with the romantic Christmas tradition of kissing under the mistletoe. The tradition itself is another that dates back to pre-Christian days, with much dispute as to its specific origins. It also features in Druidic, Norse and Greek mythologies and has wide-ranging relevance to many cultures. 

In Norse mythology, mistletoe was the only weapon that could be used to kill the god Baldur the Beautiful, orchestrated by the mischievous god Loki. In Greek myth, it allowed the hero Aeneas to visit his father in the abode of the dead. In Druidry, it is used in ceremonies and, in the past, for medicine. The tradition of kissing under the mistletoe is linked with mistletoe being a symbol of fertility. 

Long-standing and romantic as the tradition may be, those who find themselves under this iconic symbol of love might not know that it's actually a hemiparasite that grows on the branches of other trees, tapping into their nutrients to survive.

A hemiparasite is a plant which gets some or all of its food from parasitism. Mistletoe gets food from its host but also uses photosynthesis to survive.

To spread from tree to tree, mistletoe cleverly offers up its berries to birds. The seeds within the berries are coated in a sticky goo, so when the bird moves on and wipes its beak on the next tree, a seed or two is often left behind, glued in place.  

With this in mind, you'd be forgiven for thinking that the appeal of mistletoe is entirely misplaced, but don't write it off yet. It actually plays a bigger, more natural role than just being a seasonally romantic sprig. 
 

Though technically poisonous for humans to ingest, mistletoe is important to a wide range of wild species that depend on it for food. Studies have shown that areas where mistletoe has been cleared have a significant decrease in the populations of birds and other species.

Birds, such as mistle thrush and migratory blackcaps, eat the berries, a source of food in winter. Mistletoe is also key for the life cycle of the aptly named mistletoe marble moth. Mistletoe loves lime, poplar, hawthorn, and most of all, apple trees.

This dramatic and positive effect on the biodiversity surrounding it has led to some species of mistletoe being recognised as an ecological keystone species. Species like this are noted for critically affecting many other organisms in an ecosystem, playing a unique or crucial role in the way that ecosystem functions. 

It's not all about wild animals either. There is evidence suggesting some mistletoe species have value in the treatment of cancer - it's been used for this since the 1920s. The theory is that mistletoe therapy reduces the side effects of chemotherapy, improving quality of life and helping patients better tolerate the treatment. 

So, the next time you see this evergreen Christmas classic, remember that it has much more to offer than simply prompting a moment of festive romance.

Guest blog written by Vic Hill at Kent Wildlife Trust. For more interesting flora and fauna facts, subscribe to Kent Wildlife Trust's Nature is Awesome newsletter.