Stripped of their leaves, the trees are sculptural against the grey sky, revealing what is usually obscured. Trunks thick with ivy offer roosting sites for wrens and robins. Messy rook nests sway precariously in the breeze. And of course great balls of mistletoe, suspended among the bare branches as if put up for the festive season, although there all year round. Some trees have so many of the evergreen orbs in them that they appear to be in spring leaf.
For a parasite, mistletoe has a unique position in our hearts: from Greek mythologies, where it offered a gateway to the underworld, to the druids’ ceremonial links with fertility, which probably seeded our modern-day kisses under the mistletoe.
It is, in fact, a hemiparasite, gaining its energy in two ways. Rootlike structures called haustoria penetrate the bark and extract the tree’s water and nutrients. It also photosynthesises with those distinctive pairs of curved, leathery leaves. Like most parasites, it is a burden for the host tree, often affecting its growth.
However, mistletoe is disproportionately important in the ecosystem and is considered a keystone species. Without it, the creatures that benefit directly from it (like the mistle thrush and mistletoe marble moth) decline – yet the impact is wider. One study found that in woodlands where mistletoe was removed, species richness fell by 20% and a quarter of woodland birds were lost.
I find a low shrub of mistletoe on an apple tree. The pearly white berries look almost translucent against the evergreen leaves. I pick some. Just a sprig to hang for Christmas kisses, and a few berries to see if I can propagate the plant. Mistletoe is usually spread by birds eating the fleshy berries, then rubbing the slimy residue from their beaks on to the tree or excreting the intact seed. The viscous coating on the seed enables it to adhere to a branch.
I squish a few berries, finding the seeds within, my fingers coated in the gluey gunk. Like a mistle thrush cleaning its beak, I rub the sticky seeds against the branch of a mature apple tree until they hold. Germination can take months, so patience must follow. Some people spread festive cheer. I spread parasites.
• Under the Changing Skies: The Best of the Guardian’s Country Diary, 2018-2024 is published by Guardian Faber; order at guardianbookshop.com and get a 15% discount
