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Mistletoe (Phoradendron serotinum)
Photo: Jardin botanique de Montréal (Gilles Murray)
Phoradendron serotinum

What do you think of when you hear the word “mistletoe”? Sweethearts kissing in the doorway under a bunch of greenery during the holidays, perhaps? This is such an unusual and little-known plant that people often confuse it with holly. It’s quite understandable, though, since mistletoe doesn’t grow here and isn’t really part of French Quebeckers’ traditions. It may be considered a lucky plant by some and an unlucky one by others, but its intrinsic qualities have earned it plenty of attention since time immemorial.

What does it look like?

It grows on the branches of apple trees and poplars in particular, but also on hawthorns, pear trees, firs, more rarely on oaks and never, it seems, on elms or ashes. After several years’ growth it looks like a large yellowish-green ball, 60 to 90 cm across. It is highly visible, especially after the host tree’s leaves drop, because mistletoe is an evergreen. Another interesting feature is that it grows in all directions, without reaching its extremities toward the light.

Mistletoe is a hemi-parasitic plant, meaning that it doesn’t depend on its host plant for all its vital needs. Of course, it uses the host plant’s resources by taking water and minerals from it, but mistletoe has chlorophyll and can make its own sugars. So it is not a complete parasite, but a hemi-parasite.

Ancient legends, beliefs and rituals

It’s hard not to be mystified by such an unusual, enigmatic plant. For the Celts and Gauls, the plant was magical and, above all, sacred – or at least the mistletoe growing on oaks was. At a religious ceremony held six moons after the winter solstice, a druid dressed in white would climb to the top of an oak tree and use a golden knife to cut off tufts and sprigs of it. They had to be caught in a white sheet before they touched the ground, to preserve their magic power.

Afterward, two white oxen were sacrificed to consecrate the ritual. The high priest would then distribute the sprigs to the participants, shouting “mistletoe for the new year!”, and the new year would begin. People hung mistletoe in their homes or carried it on their person. It was considered a cure-all, protecting one against evil spirits, purifying the soul and healing the body, neutralizing poison, making livestock fertile and allowing the bearer to see and talk with ghosts! Just as with holly, keeping the plant in one’s home over the winter was a way of inviting in the good spirits of the forest. This may be where the custom of hanging mistletoe indoors over the holidays originated.

Later, monks called mistletoe “wood of the holy cross,” believing that it had been reduced from a tree to a parasitic bush because its wood was used to make Christ’s cross – another elegant way to explain the inexplicable. A Serbian legend said that treasure was buried at the foot of a tree in which mistletoe grew. In France and England, it was important to deck out one’s table with sprigs of mistletoe to ensure a plentiful harvest and a fertile herd. The Greeks also attributed magical powers to mistletoe, associating it with Hermes, the messenger of the gods but also the god of health. A Scandinavian legend, of which there are different versions, tells how Baldur, the supposedly invulnerable sun god, was killed by an arrow with a mistletoe shaft made by the demon Loki. The mother of the sun god, Preyla, beseeched the other gods to bring him back to life, and promised to kiss anyone who passed beneath the mistletoe. The plant became the symbol of love and forgiveness, and this legend may have led to the custom of kissing under the mistletoe.

Botanical considerations

The mistletoe to which all these beliefs apply is Viscum album, the European mistletoe that grows in Europe and Asia and, more rarely, North Africa. There are about 70 Viscum species throughout the temperate regions. It is one of the seven Viscaceae genera, a family of parasitic but chlorophyllous plants. A type of mistletoe with white fruit that grows in the southeastern United States closely resembles European mistletoe. This is Phoradendron leucarpum (syn. Phoradendron serotinum), another Viscaceae genus. Some mistletoe plants also have red or yellow fruit, and some grow in tropical regions and even in Australia.

Mistletoe is a dioecious plant, meaning that some tufts have female flowers and others, male flowers. It blooms in March and April, and the fruit ripens in August and September of the following year but does not fall until the start of the third year. Female tufts are then covered with round white fleshy, sticky berries (their stickiness which gave us the word Viscum, used by Virgil and Pliny).


Its dispersal does in fact rely mainly on birds. Mistle thrushes love mistletoe berries. Any uneaten seeds stick to their beaks with the remnants of the sticky pulp. The bird wipes its beak on a branch, and creates a seedling. Once a seed becomes stuck to a branch, it germinates and develops a holdfast with a haustorium in its centre. The haustorium penetrates the bark of the host tree, looking for sap-bearing tissue. It may extend itself beneath the bark, producing several tufts of mistletoe from a single seed. This extension naturally disrupts the tree’s anatomy, weakening the hypertrophied branch.

Medicinal properties

In the 17th century, herbalists prescribed mistletoe as a remedy for epilepsy and nervous disorders, and recommended it to regularize glandular activity, heart rhythm and digestion. These days we know more about viscine, the extract of mistletoe; strong doses can dangerously slow heart rhythm, cause convulsions, increase blood pressure and provoke abortions, while in lower doses it has beneficial effects for people suffering from high blood pressure and cardiac diseases. It seems, then, that the dose is critical. In addition, the toxicity of the plant depends on the host and its metabolism when the mistletoe is harvested. Research into mistletoe is still ongoing: Swiss laboratories are attempting to prove that its components activate the immune system and inhibit cancerous tumours.


Based on an article by Édith Morin in Quatre-Temps magazine, Vol. 20, No.4.

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