Viscum album is a species ofmistletoe in the familySantalaceae, commonly known asEuropean mistletoe,common mistletoe, or simply asmistletoe (Old Englishmistle).^[2] It is native toEurope as well as to western and southernAsia.^[3]V. album is found only rarely inNorth America, as an introduced species.

Viscum album
EvergreenViscum album growing on dormantPopulus species
Conservation status
Least Concern (IUCN 3.1)[1]
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Order:	Santalales
Family:	Santalaceae
Genus:	Viscum
Species:	V. album
Binomial name
Viscum album L.

Viscum album is ahemiparasite 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 amongChristmas decorations and symbology. In North America its cultural roles are usually fulfilled by the similar native species,Phoradendron leucarpum.

Long used in alternative medicine traditions without any scientific basis, mistletoe now is under study for pharmaceutical uses in modern medicine.

It is ahemi-parasitic evergreenshrub, which grows on the stems of other trees. The plant contains ahaustorium that connects it to the host tree by connecting the xylem and phloem of the mistletoe to that of the host tree, which allows it to receive nutrients and water.^[4] It has stems 30–100 centimetres (12–39 in) long with dichotomous branching. Theleaves 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 isdioecious and the insect-pollinatedflowers are inconspicuous, yellowish-green, 2–3 millimetres (0.079–0.118 in) diameter. Thefruit is a white or yellowberry, and except for very rarely, containing oneseed embedded in the very sticky, glutinous fruit pulp.

It is commonly found in the crowns of broad-leaved trees, particularlyapple,lime (linden),hawthorn, andpoplar.^[5]

European mistletoe is the only multicellular organism known to lack a functioningrespiratory complex I in itselectron transport chain, a protein that is essential for the creation of useful energy for its cells.^[6] It is believed to survive by obtainingadenosine triphosphate and energy-rich compounds from its host as well as reorganizing its other respiratory complexes and slowing its growth and energy requirements.^[7]

The mistletoe was one of the many species originally described byLinnaeus. Its species name is theLatin adjectivealbus, "white". It and the other members of the genusViscum were originally classified in the mistletoe familyViscaceae, but this family has since been reclassified into the larger familySantalaceae.

Severalsubspecies are commonly accepted.^{[8][9][10][11]} They differ in fruit colour, leaf shape and size, and most obviously in the host trees used.

• Viscum album subsp.abietis (Wiesb.) Abromeit.Central Europe. Fruit white; leaves up to 8 centimetres (3.1 in). OnAbies.
• Viscum album subsp.album. Europe,southwest Asia east toNepal. Fruit white; leaves 3–5 centimetres (1.2–2.0 in). OnMalus,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. OnLarix,Pinus,Picea.
• Viscum album subsp.meridianum (Danser) D.G.Long.Southeast Asia. Fruit yellow; leaves 3–5 centimetres (1.2–2.0 in). OnAcer,Carpinus,Juglans,Prunus,Sorbus.
• Viscum album subsp.creticum has recently been described from easternCrete.^[12] Fruit white; leaves short. OnPinus brutia.
• Viscum album subsp.coloratum Kom. is treated by theFlora of China^[9] as a distinct speciesViscum coloratum (Kom) Nakai.

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The European mistletoe has one of the largestgenomes of all organisms, at about 90 billion base pairs (compared to ~3 billion bp in thehuman genome). It encodes 39,092 distinctopen reading frames encoding 32,064proteins.^[13]

If ingested in a concentrated form, such as a herbal tea infusion, European mistletoe is potentially fatal. Otherwise, people have been known to become seriously ill from eating the berries.^[14]

The toxiclectinviscumin has been isolated fromViscum album.^[15] Viscumin is a cytotoxic protein (ribosome inactivating protein, or RIP) that binds togalactose residues of cell surfaceglycoproteins and may be internalised byendocytosis.^[16] 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 toricin andabrin.^[15][16]

Some birds have immunity to the toxin and enjoy the berries, especially themistle thrush that is so named because mistletoe is their favourite food. Birds are especially important in distributing the seeds of the plant to new locations in the trees in which it will grow.

European mistletoe features in many myths and legends, from early written sources into the modern period. In cultures across pre-Christian Europe, mistletoe was often seen as a representation of divine male essence (and thus romance, fertility, and vitality).^[17]

Mistletoe figured prominently inGreek mythology, and is believed to be theGolden Bough ofAeneas, ancestor of theRomans.^[18] In Ancient Greek mythology, mistletoe was used by heroes to access the underworld.^[19] TheRomans associated mistletoe with peace, love, and understanding. They hung mistletoe over doorways to protect the household.^[20]

Modern botanists believe the described mistletoe species in oak trees wasLoranthus europaeus.^{[citation needed]}

"Things" are governing assemblies or forums in early Germanic society and similar gatherings appear in German mythology and historical accounts of the religious and social practices of the culture. Mistletoe appears in the thirteenth centuryProse Edda account of German traditions. One account relates that the goddessFrigg required that everything swear an oath not to hurt her sonBaldr, except for mistletoe, because "it seemed too young" to be a threat to her son. Atthing gatherings of deities that followed, other deities began to have fun by shooting at him, or hurling stones, without him being injured at all. At one gathering however,Loki, wishing Baldr dead, tricked the blind godHöðr who was Baldr's brother, into throwing mistletoe at Baldr, killing him.^[21]

In another version of the myth inGesta Danorum, Baldr and Höðr are rival suitors forNanna, and Höðr kills Baldr with a sword namedMistilteinn (Old Norse "mistletoe").^[22] Additionally, a sword by the same name also appears inHervarar saga ok Heiðreks andHrómundar saga Gripssonar.^[23]

When Christianity became widespread in Europe after the third century AD, the ancient religious or mystical respect for the mistletoe plant was absorbed only as a cultural tradition. In some way that is not presently understood, this may have led to the widespread custom ofkissing under the mistletoe plant during the Christmas season.

The earliest documented evidence of the tradition of kissing under the mistletoe dates from sixteenth 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 theCross was made, but afterward it was condemned to live on only as a parasite.^[24]

Mistletoe is commonly used as aChristmas decoration, although such use was rarely alluded to until the eighteenth century.^[25] According to custom, the mistletoe must not touch the ground between its cutting and its removal as the last of Christmas greens atCandlemas. It may remain hanging throughout the year, often to preserve the house fromlightning or fire, until it is replaced the following Christmas Eve.^[25][26] This tradition has spread throughout the English-speaking world, but is largely unknown in the rest of Europe. (The similar native speciesPhoradendron leucarpum is used inNorth America in lieu of the EuropeanViscum album.)

According to an old Christmas custom, a man and a woman who meet under a hanging of mistletoe were obliged tokiss. The custom may be ofScandinavian origin.^[27] It was alluded to as common practice in 1808^[28] and described in 1820 by American authorWashington Irving in hisThe 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.^[29]

In Germany, the Christmas tradition is that people who kiss under mistletoe will have an enduring love or are bound to marry one another.^[30]

Every year, the UK town ofTenbury Wells holds a mistletoe festival and crowns a 'Mistletoe Queen'.^[20]

Mistletoe is thecounty flower ofHerefordshire. It was voted such in 2002, following a poll by the wild plant conservation charityPlantlife.^[31]

The Latin wordviscum, 'mistletoe, birdlime' is the source ofviscous.^[32]

The sticky juice of mistletoe berries was used to makebirdlime, anadhesive totrap small animals or birds.^[33]

Mistletoe is an ingredient ofbiska, apomace brandy-based liquor made inIstria.^[34]

Mistletoe leaves and young twigs are used by herbalists and preparations made from them are popular in Europe, especially inGermany, for attempting to treat circulatory and respiratory system problems.^[35][36][37] Use of mistletoe extract in the treatment of cancer originated withRudolf Steiner, the founder ofAnthroposophy.^[38]

Althoughlaboratory andanimal experiments have suggested that mistletoe extract may affect theimmune system and be able to kill some kinds of cancer cells, as of 2024, there is littleevidence of its benefit to people with cancer.^[39][40] However, more pharmaceutical research on mistletoe is in progress.^[41][42]

•  
  19th century illustration byFranz Eugen Köhler
•  
  On an apple tree inEssex,England
•  
  On an apple tree in Essex, England
•  
  In abundance on an apple tree (inFranche-Comté)
•  
  Sticky seed on a branch
•  
  InVersailles,France
•  
  Fruit ofV. a. album, inPoland
•  
  V. a. austriacum onPinus sylvestris, Poland
•  
  Fruit, inGryfino, NW Poland
•  
  Viscum album inFrance, winter
•  
  Viscum album inUkraine, spring
•  
  Cross section of wood

• Christmas decoration
• List of unproven and disproven cancer treatments

• Tubeuf, Karl; Neckel, Gustav (1923).Monographie der Mistel. München und Berlin, Oldenbourg.
• Huxley, A., ed. (1992).New RHS Dictionary of Gardening. Vol. 4. p. 676.ISBN 0-333-47494-5.

• Distribution maps of Viscum album
• Flora of Pakistan:Viscum album
• Viscum album subsp.creticum