Viscum album

Viscum album
Viscum album growing on a Populus species
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Core eudicots
Order:	Santalales
Family:	Santalaceae (Viscaceae)
Genus:	Viscum
Species:	V. album
Binomial name
Viscum album L.

Viscum album is a species of mistletoe in the family Santalaceae, commonly known as European mistletoe, common mistletoe or simply as mistletoe (Old English mistle).^[1] It is native to Europe and western and southern Asia.

Viscum album is a hemiparasite on several species of trees, from which it draws water and nutrients. It has a significant role in European mythology, legends, and customs. In modern times, it is commonly featured in Christmas decoration and symbology. (V. album is found only rarely in North America, as an introduced species; its cultural roles are usually fulfilled by the similar native species Phoradendron leucarpum.)

Description

It is a hemi-parasitic shrub, which grows on the stems of other trees. It has stems 30–100 centimetres (12–39 in) long with dichotomous branching. The leaves are in opposite pairs, strap-shaped, entire, leathery textured, 2–8 centimetres (0.79–3.15 in) long, 0.8–2.5 centimetres (0.31–0.98 in) broad and are a yellowish-green in colour. This species is dioecious and the insect-pollinated flowers are inconspicuous, yellowish-green, 2–3 millimetres (0.079–0.118 in) diameter. The fruit is a white or yellow berry containing one (very rarely several) seed embedded in the very sticky, glutinous fruit pulp.

It is commonly found in the crowns of broad-leaved trees, particularly apple, lime (linden), hawthorn and poplar.^[2]

Classification

The mistletoe was one of the many species originally described by Linnaeus. Its species name is the Latin adjective albus "white". It and the other members of the genus Viscum were originally classified in the mistletoe family Viscaceae, but this family has since been sunk into the larger family Santalaceae.

Subspecies

Several subspecies are commonly accepted.^[3][4][5][6] They differ in fruit colour, leaf shape and size, and most obviously in the host trees utilised.

• Viscum album subsp. abietis (Wiesb.) Abromeit. Central Europe. Fruit white; leaves up to 8 centimetres (3.1 in). On Abies.
• Viscum album subsp. album. Europe, southwest Asia east to Nepal. Fruit white; leaves 3–5 centimetres (1.2–2.0 in). On Malus, Populus, Tilia, and less often on numerous other species, including (rarely) Quercus.
• Viscum album subsp. austriacum (Wiesb.) Vollmann. Fruit yellow; leaves 2–4 centimetres (0.79–1.57 in). Central Europe. On Larix, Pinus, Picea.
• Viscum album subsp. meridianum (Danser) D.G.Long. Southeast Asia. Fruit yellow; leaves 3–5 centimetres (1.2–2.0 in). On Acer, Carpinus, Juglans, Prunus, Sorbus.
• Viscum album subsp. creticum has recently been described from eastern Crete.^[7] Fruit white; leaves short. On Pinus brutia.
• Viscum album subsp. coloratum Kom. is treated by the Flora of China^[4] as a distinct species Viscum coloratum (Kom) Nakai.

Toxicity

The toxic lectin viscumin has been isolated from Viscum album.^[8] Viscumin is a cytotoxic protein (Ribosome inactivating protein, or RIP) that binds to galactose residues of cell surface glycoproteins and may be internalised by endocytosis.^[9] Viscumin strongly inhibits protein synthesis by inactivating the 60 S ribosomal subunit. The structure of this protein is very similar to other RIPs, showing the most resemblance to ricin and abrin ^[8][9]

Culture, folklore, and mythology

European mistletoe has always attracted popular interest and has been surrounded by a number of myths and legends. In cultures across pre-Christian Europe, mistletoe was seen as a representation of divine male essence (and thus romance, fertility and vitality). It still plays a role in the folklore of some countries.

Ancient Greece and Rome

Mistletoe figured prominently in Greek mythology, and is believed to be The Golden Bough of Aeneas, ancestor of the Romans.^[10]

Celtic world

According to Pliny the Elder, the Celts considered it a remedy for barrenness in animals and an antidote to poison, and sacred when growing on oak trees (where it is rare). He describes a Celtic ritual sacrifice and banquet at which a druid dressed in white would climb an oak tree to collect mistletoe using a golden sickle.^[11] (This legend is often referred to in the popular Asterix comic books.)

Modern druids may use the native American Phoradendron leucarpum as well as other mistletoe species.^[12]

Scandinavia

Each arrow overshot his head (1902) by Elmer Boyd Smith, depicting the blind god Höðr shooting his brother, the god Baldr, with a mistletoe arrow

According to the 13th century Prose Edda, the goddess Frigg had all living and inanimate things swear an oath not to hurt her son Baldr. At a gathering, other gods tested the oath by hurling stones, arrows and fire at him, all in vain. But Frigg had not demanded the oath from mistletoe, because "it seemed too young" for that.^[13] By a scheming of Loki, Baldr's brother, the blind god Höðr made an arrow from mistletoe and killed Baldr with it.

In the Gesta Danorum version of the story, Baldr and Höðr are rival suitors, and Höðr kills Baldr with a sword named Mistilteinn (Old Norse "mistletoe"). In addition, a sword by the same name appears in various other Norse legends.

Christianity

Mistletoe postcard, circa 1900

When Christianity became widespread in Europe after the third century AD, the religious or mystical respect for the mistletoe plant was integrated to an extent into the new religion. In some way that is not presently understood, this may have led to the widespread custom of kissing under the mistletoe plant during the Christmas season. The earliest documented case of kissing under the mistletoe dates from 16th century England, a custom that was apparently very popular at that time.

Winston Graham reports a Cornish tradition that mistletoe was originally a fine tree from which the wood of the Cross was made, but afterwards it was condemned to live on only as a parasite.^[14]

Mistletoe is commonly used as a Christmas decoration, though such use was rarely alluded to until the 18th century.^[15] According to custom, the mistletoe must not touch the ground between its cutting and its removal as the last of Christmas greens at Candlemas. It may remain hanging throughout the year, often to preserve the house from lightning or fire, until it is replaced the following Christmas Eve.^[16][17] The tradition has spread throughout the English-speaking world, but is largely unknown in the rest of Europe. (The similar native species Phoradendron leucarpum is used in North America in lieu of the European Viscum album.)

According to an old Christmas custom, a man and a woman who meet under a hanging of mistletoe were obliged to kiss. The custom may be of Scandinavian origin.^[18] It was alluded to as common practice in 1808^[19] and described in 1820 by American author Washington Irving in his The Sketch Book of Geoffrey Crayon, Gent.:

The mistletoe is still hung up in farm-houses and kitchens at Christmas, and the young men have the privilege of kissing the girls under it, plucking each time a berry from the bush. When the berries are all plucked the privilege ceases.^[20]

Local symbol

Mistletoe is the County flower of Herefordshire. It was voted such in 2002 following a poll by the wild plant conservation charity Plantlife.^[21]

Uses

Flavoring

Mistletoe is an ingredient of pomace brandy based liquor biska made in Istra, Croatia.

Medicine

Mistletoe leaves and young twigs are used by herbalists, and it is popular in Europe, especially in Germany, for treating circulatory and respiratory system problems.^[22][23][24] Use of mistletoe extract in the treatment of cancer originated with Rudolf Steiner, the founder of Anthroposophy. He compared the parasitic nature of the mistletoe plant to that of cancer, and believed that cancer represents a faltering of the body's spiritual defenses.^[25][26] Some anthroposophical mistletoe preparations are diluted homeopathically. Mistletoe extract is sold as Iscador, Helixor, and several other trade names.^[25]

Available clinical evidence does not support claims of anti-cancer effect, quality of life, or other outcomes from the use of mistletoe extract. Research has likewise shown little or no improvement in rigorous trials.^[25][27][28] Public interest in the United States was spurred in 2001 following actress Suzanne Somers' decision to use Iscador in lieu of chemotherapy following her treatment for breast cancer using surgery and radiotherapy.^[29][30]

Findings from over 50 clinical trials using mistletoe extracts in patients with cancer have been published. Recent reviews of many studies taken together have looked at the effects of mistletoe on quality of life, survival, and symptom relief in different types of cancer:

Quality of life was measured in a review that included 26 randomized clinical trials. Of these, 22 trials showed patients had improved quality of life. All 10 nonrandomized, controlled clinical trials reviewed also reported the same benefits. Chemotherapy-related fatigue, nausea and vomiting, depression, emotional well-being, and concentration improved. Some of the studies were well designed, while others had weaknesses.^[31]

Bird trapping

The sticky juice of mistletoe berries was used to make birdlime, an adhesive to trap small animals or birds.^[32]

Decoration

European mistletoe and its North American surrogate Phoradendron leucarpum are harvested commercially for use as Christmas decoration.

Gallery

• 

  19th century illustration by Franz Eugen Köhler

• 

  On an apple tree in Essex, England

• 

  On an apple tree in Essex, England

• 

  Sticky seed on a branch

• 

  In Versailles, France

• 

  Fruit of V. a. album, in Poland

• 

  V. a. austriacum on Pinus sylvestris, Poland

• 

  Fruit, in Gryfino, NW Poland.

• 

  Viscum album in France, Winter

• 

  Viscum album in Ukraine, Spring

• 

  Cross section of wood

References

Wikimedia Commons has media related to Viscum album.

Notes

General references

1. Flora of Pakistan: Viscum album
2. Viscum album subsp. creticum
3. Huxley, A., ed. (1992). New RHS Dictionary of Gardening 4: 676. ISBN 0-333-47494-5