Mistletoe: a sign of unspoiled nature
in the Ariège Pyrenees
From time immemorial people have attributed sacred or medicinal virtues to mistletoe. How can one fail to notice those green tufts with white berries perched in the leafless trees in winter? And as mistletoe grows only rarely on oaks -- less than 15 identified in all of France -- a tree symbolising strength and power, it's not surprising that it was so sought after by the Druids.
Mistletoe is also prized by birds, but it doesn't love them all back equally. It quite likes the Thrushes that eat the entire berry. They will excrete it intact a bit further away with their droppings. That's not the case with Woodpigeons whose powerful gastric acids destroy the seed, despite its thick husk, as it passes through the intenstinal tract. Mistletoe detests Tits (Blue and Great) and Nuthatches because they crack open the seed to eat it. It far prefers the Black-headed Warbler who is content to eat the internal mucilage of the berry and get rid of the seeds stuck to its beak by rubbing it against the branches and thus sowing the seed close to home.
As soon as mistletoe germinates it emits a sucker -- it has no roots -- which will draw out the raw sap of the tree; that is, the mineral salts that trees roots have drawn from the soil. Seemingly because of this, though we're not sure exactly why, the branch on which the mistletoe has taken hold is thinner afterwards. But mistletoe is only partly parasitic. If it's green it's because it contains chlorophyll which allows photosynthesis from sunlight. And it remains green all the time because its leaves, instead of foolishly falling in autumn like those of trees, live for 18 months. But mistletoe sends out a new shoot every year, so one need only count the articulations to know its age.
In addition, mistletoe is very prudish--Madame and Monsieur sleep apart. Certain shoots have only male flowers; the others, which have the berries, are female. It's from these berries with the viscus interior--the Latin name for mistletoe is Viscum album--that we used to use to make glue; this substance is also found under the bark. It is also a medicinal plant that is active against certain cancers in slowing cell division. However, that doesn't prevent it from being toxic at high doses. In the past it was believed to cause cows to produce more milk. Marcailhou d'Aymeric, a pharmaceutical botanist from Ax-les-Thermes in Ariège, reported in 1911 that it was fed to sheep in the winter. Even slugs consume the young shoots. They can manage this because because mistletoe can grow upside down, which quite rare in plants. And it must also grow backwards: in effect the tree forms a new layer of wood each year under the bark and the sucking root must therefore take a step backward each year, otherwise the source will dry up. And this no matter which direction it's growing in!
This is one plant that we do encourage you to cut to decorate your door. For one thing, you might spare the land owner a fine: French laws from 1888 and 1893, never repealed, oblige property owners to destroy mistletoe.
And thus the New Year tradition will be respected (with our many happy returns).
Association des Naturalistes de l'Ariège