Mistletoe
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Mistletoe is the common name for various parasitic plants of the families Santalaceae (in the section of the family formerly separated as Viscaceae) and Loranthaceae.
The name was originally applied to Viscum album (European Mistletoe, Santalaceae; the only species native in Great Britain and much of Europe), and subsequently to other related species, including Phoradendron leucarpum (the Eastern Mistletoe of eastern North America, also Santalaceae). In an example of convergent evolution, several less related but superficially very similar plants in the Loranthaceae are also so similar that they have also been called mistletoes.
The European Mistletoe is readily recognised by its smooth-edged oval leaves in pairs along the woody stem, and waxy white berries in dense clusters of 2-6 together. American Mistletoe is similar, but has shorter, broader leaves and longer clusters of ten or more berries together.
Mistletoe biodiversity is markedly higher in subtropical and tropical climates; Australia has 85 species, of which 71 are in Loranthaceae, and 14 in Santalaceae.
The species grow on a wide range of trees, and can eventually prove fatal to them where infestation is heavy, though damage more commonly only results in growth reduction. Most mistletoes are only partial parasites, bearing evergreen leaves that carry out some photosynthesis of their own, relying on the host mainly for mineral nutrients from the ground. The genus Arceuthobium (dwarf mistletoe; Santalaceae) has dispensed with even this, becoming a total parasite relying on its host plant for photosynthesis as well as nutrients.
Most mistletoes are spread by birds (e.g. the Mistle Thrush in Europe, and the Phainopepla in southwestern North America) which eat the berries. The seeds are excreted in their droppings and stick to twigs, or more commonly the bird grips the fruit in its bill which squeezes the sticky coated seed out to the side which the bird then wipes clean on a suitable branch. The seeds are coated with a sticky gum, Viscin, which hardens and attaches the seed firmly to its future host.
The word 'mistletoe' is of uncertain etymology; it may be related to German Mist, another word for dung, but Old English mistel was also used for basil.
Uses and mythology
The leaves and young twigs are the parts used by herbalists, and it is very popular in Europe, especially in Germany, for treating circulatory and respiratory system problems as well as for tumors, even malignant ones.
Mistletoe figured prominently in Norse mythology (whence the modern Western custom of kissing under bunches of it hung as holiday decorations). The god Baldur was killed with a weapon made of mistletoe. In Celtic mythology and in Druid rituals, it was considered an antidote to poison, but contact with its berries produces a rash similar to the poison ivy rash in people who are sensitive to it (as many are), so the whole plant came to be thought of as poisonous.
Mistletoe has sometimes been nick-named the "vampire plant" because it can probe beneath tree bark to drain water and minerals, enabling it to survive during drought (see vampirism).
Nowadays, mistletoe is commonly used as a Christmas decoration, with Viscum album being used in Europe while in North America, Phoradendron leucarpum is used instead.
External Links
- About mistletoe (http://www.mistletoe.org.uk)
- Parasitic Plant Connection (http://www.science.siu.edu/parasitic-plants/)
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de:Mistel eo:Blanka visko fr:Gui (plante) it:Viscum album nl:Maretak pl:Jemioła zh:槲寄生