''Viscum'' is a genus of about 70–100 species of

mistletoe Mistletoe is the common name for obligate hemiparasitic plants in the order Santalales. They are attached to their host tree or shrub by a structure called the haustorium, through which they extract water and nutrients from the host plant. ...

s, native to temperate and tropical regions of

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...

and

Australasia Australasia is a region that comprises Australia, New Zealand and some neighbouring islands in the Pacific Ocean. The term is used in a number of different contexts, including geopolitically, physiogeographically, philologically, and ecologica ...

. Traditionally, the genus has been placed in its own family

Viscaceae Viscaceae is a taxonomic family name of flowering plants. In this circumscription, the family includes the several genera of mistletoes. This family name is currently being studied and under review as in past decades, several systems of plant taxon ...

, but recent genetic research by the Angiosperm Phylogeny Group shows this family to be correctly placed within a larger circumscription of the

sandalwood Sandalwood is a class of woods from trees in the genus ''Santalum''. The woods are heavy, yellow, and fine-grained, and, unlike many other aromatic woods, they retain their fragrance for decades. Sandalwood oil is extracted from the woods for us ...

family, Santalaceae. Its name is the origin of the English word

viscous The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the inter ...

, after the Latin ''viscum'', a sticky

bird lime Birdlime or bird lime is an adhesive substance used in trapping birds. It is spread on a branch or twig, upon which a bird may land and be caught. Its use is illegal in many jurisdictions. Manufacture Historically, the substance has been prep ...

made from the plants' berries. They are woody, obligate hemiparasitic

shrub A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees ...

s with branches long. Their hosts are woody shrubs and

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...

s. The foliage is dichotomously or verticillately branching, with opposite pairs or whorls of green

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

which perform some

photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...

(minimal in some species, notably ''V. nudum''), but with the plant drawing its mineral and water needs from the host tree. Different species of ''Viscum'' tend to use different host species; most species are able to use several different host species. The

flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...

s are inconspicuous, greenish-yellow, diameter. The

fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...

is a

berry A berry is a small, pulpy, and often edible fruit. Typically, berries are juicy, rounded, brightly colored, sweet, sour or tart, and do not have a stone or pit, although many pips or seeds may be present. Common examples are strawberries, raspb ...

, white, yellow, orange, or red when mature, containing one or more

seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...

s embedded in very sticky juice; the seeds are dispersed when

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

s (notably the

mistle thrush The mistle thrush (''Turdus viscivorus'') is a bird common to much of Europe, temperate Asia and North Africa. It is a year-round resident in a large part of its range, but northern and eastern populations migrate south for the winter, often ...

) eat the fruit, and remove the sticky seeds from the bill by wiping them on tree branches where they can germinate.

Toxicity in the genus ''Viscum''

''Viscum'' species are poisonous to humans; eating the fruit causes a weak pulse and acute gastrointestinal problems including stomach pain and

diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin wi ...

. At least one of the active ingredients is the

lectin Lectins are carbohydrate-binding proteins that are highly specific for sugar groups that are part of other molecules, so cause agglutination of particular cells or precipitation of glycoconjugates and polysaccharides. Lectins have a role in rec ...

viscumin, which is intensely toxic. It inhibits protein synthesis by catalytically inactivating ribosomes. In spite of this, many species of animals are adapted to eating the fruit as a significant part of their diet.

David M. Watson David M. Watson is an Australian ornithologist and ecologist who is also a scientific specialist on mistletoes. He served on the New South Wales Threatened Species Scientific Committee from 2015 until publicly resigning in June 2017 in protest ...

, "Mistletoe-A Keystone Resource in Forests and Woodlands Worldwide" ''Annual Review of Ecology and Systematics'' 32 (2001:219–249).

Fossil record

†''Viscum morlotii'' from the early

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

, has been described from

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

leaf compressions that have been found in the Kristina Mine at

Hrádek nad Nisou Hrádek nad Nisou (; german: Grottau, pl, Gródek nad Nysą) is a town in Liberec District in the Liberec Region of the Czech Republic. It has about 7,700 inhabitants. The town centre is well preserved and is protected by law as an urban monument ...

North Bohemia North Bohemia ( cs, Severní Čechy, german: Nordböhmen) is a region in the north of the Czech Republic. Location North Bohemia roughly covers the present-day NUTS regional unit of ''CZ04 Severozápad'' and the western part of ''CZ05 Severovýc ...

, the

Czech Republic The Czech Republic, or simply Czechia, is a landlocked country in Central Europe. Historically known as Bohemia, it is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the southeast. The ...

Selected species

Viscum coloratum on Aspen about Khabarovsk Russia

* '' Viscum album'' – European mistletoe * ''

Viscum articulatum ''Viscum'' is a genus of about 70–100 species of mistletoes, native to temperate and tropical regions of Europe, Africa, Asia and Australasia. Traditionally, the genus has been placed in its own family Viscaceae, but recent genetic research by ...

'' * ''

Viscum bancroftii ''Viscum'' is a genus of about 70–100 species of mistletoes, native to temperate and tropical regions of Europe, Africa, Asia and Australasia. Traditionally, the genus has been placed in its own family Viscaceae, but recent genetic research by ...

'' * ''

Viscum capense ''Viscum capense'' (common name, Cape mistletoe) is a species of Mistletoe that is indigenous to South Africa, especially the area from Cape Town, northwards along the coast up to Namibia, and eastwards as far as the Eastern Cape province. Th ...

'' – Cape mistletoe (South Africa) * '' Viscum coloratum'' – Korean mistletoe (Korea) * ''

Viscum combreticola ''Viscum combreticola'', the Combretum mistletoe, is a leafless, dioecious mistletoe shrub, occurring from southern to tropical Africa, in a broad zone following the Rift Valleys. Though it is typically a hemiparasite of '' Combretum'' species, i ...

'' Engl. – combretum mistletoe * '' Viscum cruciatum'' – red-berried mistletoe * ''

Viscum diospyrosicola ''Viscum'' is a genus of about 70–100 species of mistletoes, native to temperate and tropical regions of Europe, Africa, Asia and Australasia. Traditionally, the genus has been placed in its own family Viscaceae, but recent genetic research by ...

'' * ''

Viscum exile ''Viscum exile'' is a species of mistletoe in the family Santalaceae. It is a parasitic plant native to Sulawesi. References External links''Viscum exile'' occurrence datafrom GBIF {{taxonbar, from=Q18082504 exile Exile is primarily pena ...

'' * '' Viscum fargesii'' * ''

Viscum liquidambaricola ''Viscum'' is a genus of about 70–100 species of mistletoes, native to temperate and tropical regions of Europe, Africa, Asia and Australasia. Traditionally, the genus has been placed in its own family Viscaceae, but recent genetic research by ...

'' * ''

Viscum loranthi ''Viscum'' is a genus of about 70–100 species of mistletoes, native to temperate and tropical regions of Europe, Africa, Asia and Australasia. Traditionally, the genus has been placed in its own family Viscaceae, but recent genetic research by ...

'' * ''

Viscum minimum ''Viscum minimum'' is a species of mistletoe in the family Santalaceae. It is a parasitic plant native to South Africa. Description In its native habitat ''Viscum minimum'' uses two species of succulents, '' Euphorbia polygona'' and ''Euphorbia ...

'' * ''

Viscum monoicum ''Viscum'' is a genus of about 70–100 species of mistletoes, native to temperate and tropical regions of Europe, Africa, Asia and Australasia. Traditionally, the genus has been placed in its own family Viscaceae, but recent genetic research by ...

'' * '' Viscum multinerve'' * ''

Viscum nudum ''Viscum'' is a genus of about 70–100 species of mistletoes, native to temperate and tropical regions of Europe, Africa, Asia and Australasia. Traditionally, the genus has been placed in its own family Viscaceae, but recent genetic research by ...

'' * ''

Viscum orientale ''Viscum'' is a genus of about 70–100 species of mistletoes, native to temperate and tropical regions of Europe, Africa, Asia and Australasia. Traditionally, the genus has been placed in its own family Viscaceae, but recent genetic research by ...

'' * ''

Viscum ovalifolium ''Viscum'' is a genus of about 70–100 species of mistletoes, native to temperate and tropical regions of Europe, Africa, Asia and Australasia. Traditionally, the genus has been placed in its own family Viscaceae, but recent genetic research by ...

'' * ''

Viscum rotundifolium ''Viscum rotundifolium'', the red-berry mistletoe, is a variable, wide-ranging and monoecious mistletoe Mistletoe is the common name for obligate hemiparasitic plants in the order Santalales. They are attached to their host tree or shrub ...

'' L.f. – round-leaved or red-berry mistletoe * ''

Viscum scurruloideum ''Viscum'' is a genus of about 70–100 species of mistletoes, native to temperate and tropical regions of Europe, Africa, Asia and Australasia. Traditionally, the genus has been placed in its own family Viscaceae, but recent genetic research by ...

'' * ''

Viscum triflorum ''Viscum'' is a genus of about 70–100 species of mistletoes, native to temperate and tropical regions of Europe, Africa, Asia and Australasia. Traditionally, the genus has been placed in its own family Viscaceae, but recent genetic research by ...

'' * ''

Viscum whitei ''Viscum'' is a genus of about 70–100 species of mistletoes, native to temperate and tropical regions of Europe, Africa, Asia and Australasia. Traditionally, the genus has been placed in its own family Viscaceae, but recent genetic research by ...

'' * ''

Viscum yunnanense ''Viscum'' is a genus of about 70–100 species of mistletoes, native to temperate and tropical regions of Europe, Africa, Asia and Australasia. Traditionally, the genus has been placed in its own family Viscaceae, but recent genetic research by ...

References

Flora of China: ''Viscum''Flora of Pakistan: ''Viscum''Flora Europaea: ''Viscum''
*

{{Taxonbar, from=Q147345 Parasitic plants Santalales genera