Guest blog by: Laura Cooper
Whilst many species of plants are referred to as mistletoe, the icon of Christmas is the European Mistletoe Viscum album. Mistletoe has a varied reputation; it is a symbol of Christmas and druidic ritual, a poisoner and a matchmaker.
The plant itself belongs to the Santalacea or sandalwood family. It is found throughout much of Europe, but in the UK is localized to the central south. V. album lacks its own trunk and instead grows in the crowns of host trees including apple, lime, hawthorn and poplar when its seeds are dispersed by birds smearing the sticky fruit and seed from their beaks onto the bark of the host. V. album is not a true parasite but a hemiparasite. This is because whilst the seedling sends its haustorium from the roots through the bark of the host to induce the host’s xylem vessels to supply it with water and nutrients, V. album makes its own sugars through photosynthesis. A heavy infestation of mistletoe can take over the entire crown of a tree preventing the host photosynthesising and building its own tissue which can lead to the death of the host.
V. album owes its toxicity to large amounts of the alkaloid tyramine throughout the plant, which is also present at lower levels in foods including cheese. As with most toxins, it is the dose that makes the poison, not the chemical. Whilst little research has been done on the effects of consuming V. album, it has been reported that consuming enough of the leaves or berries can result in nausea, abdominal pain, diarrhea and death. However, the well-known risks of mistletoe means poisoning cases are very rare. As the Poison Garden argues, artificial mistletoe is likely more dangerous as a choking hazard to children than live mistletoe is as a poison.
Whilst mistletoe is commonly linked with druids, the only account of a druid ceremony involving mistletoe comes from Pliny the Elder. He details a banquet and ritual sacrifice where a druid would climb an oak tree, cut the mistletoe with a golden sickle and drop it into a cloak to prevent it touching the ground and losing its power. The link between druids and mistletoe was picked up in the revival of druidry in the 18th century and today druids carry out a similar ceremony, without the human sacrifice! The tradition of kissing under the mistletoe at Christmas is not a Christian tradition but also derives from the association of mistletoe with fertility in druidic mythology. Christianity has a less favorable relationship with mistletoe, as according to tradition mistletoe wood was used to makes Christ’s cross and ever since could not grow upon the earth so was condemned to parasitic life.
Mistletoe has also been used as a medicine historically, including as an epilepsy treatment. Today, injection of extracts of mistletoe has been used as an anti-cancer treatment in alternative and complementary healthcare. Whilst it has been shown to kill cancer cells, the few trials done were inconclusive or poorly done, and the NHS advises that there is currently no reliable evidence that mistletoe is effective at treating cancer.
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