|Viscum album growing on a Populus species|
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). It is native to Europe and western and southern Asia.
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.
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.
- 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. Fruit white; leaves short. On Pinus brutia.
- Viscum album subsp. coloratum Kom. is treated by the Flora of China as a distinct species Viscum coloratum (Kom) Nakai.
Cultural significance and uses
The toxic lectin viscumin has been isolated from Viscum album. 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. 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 
Mythology and symbolism
Mistletoe has always attracted popular interest and has been surrounded by a number of myths and legends. In some countries it plays a part in Christmas festivities. Pliny recorded an ancient druidic belief that mistletoe collected from oaks had special qualities; the same theme is reprised in the popular Asterix comic books. In Norse myth, an arrow made of mistletoe was the only thing that was able to kill the god Balder. The goddess Frigg had asked all other things to vow not to hurt Balder, but she had ignored the mistletoe because it seemed too small to be dangerous.
Fruit of V. a. album, Poland
V. a. austriacum on Pinus sylvestris, Poland
19th century illustration by Franz Eugen Köhler
Viscum album in France, Winter
Viscum album in Russia, Spring
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- D. Zuber (2004). Biological flora of Central Europe: Viscum album L. Flora 199, 181-203
- Tree News, Spring/Summer 2005,Publisher Felix Press
- Flora Europaea: Viscum album
- Flora of China: Viscum album
- Bean, W. J. (1980). Trees and Shrubs Hardy in the British Isles 8th ed. 4: 725-726. ISBN 0-7195-2428-8
- Blamey, M. & Grey-Wilson, C. (1989). The Illustrated Flora of Britain and Northern Europe. Hodder & Stoughton. ISBN 0-340-40170-2.
- Böhling, N., Greuter, W., Raus, T., Snogerup, B., Snogerup, S. & Zuber, D. (2003). Notes on the Cretan mistletoe, Viscum album subsp. creticum subsp. nova (Loranthaceae/Viscaceae). Israel J. Pl. Sci. 50 (Suppl.): 77-84.
- Olsnes S, Stirpe F, Sandvig K, Pihl A (November 1982). "Isolation and characterization of viscumin, a toxic lectin from Viscum album L. (mistletoe)". The Journal of Biological Chemistry 257 (22): 13263–70. PMID 7142144. Retrieved 2009-06-22.
- Stirpe F, Sandvig K, Olsnes S, Pihl A (November 1982). "Action of viscumin, a toxic lectin from mistletoe, on cells in culture". The Journal of Biological Chemistry 257 (22): 13271–7. PMID 7142145. Retrieved 2009-06-22.