|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 a Norse myth, Balder was the most beloved by the other gods. They wanted to protect him from all the dangers in the world, so his mother Frigg took an oath from fire, water, metal, stone and every living thing that they would never hurt Balder. At a gathering they tested the oath. Stones, arrows and flame were all hurled at him, and nothing hurt him. But there was one god that wasn't so enamoured of Balder, the god of mischief Loki. Loki discovered that Frigg had forgotten to ask mistletoe; a tiny, seemingly harmless plant and completely overlooked. Loki fashioned a dart out of mistletoe and it killed Balder. Frigg was heartbroken. She decreed that that mistletoe would never be used again as a weapon and that she would place a kiss on anyone who passed under it. So now we hang mistletoe underneath our doors during the holidays, so that we will never overlook it again.
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
|Wikimedia Commons has media related to Viscum album.|
- 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.