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| Viscum alba
berries. |
Viscum
Viscum is a genus of about 70-100 species of
mistletoe,
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 the
Angiosperm Phylogeny Group shows this family to be correctly placed within a
larger circumscription of the
sandalwood
family,
Santalaceae.
They are woody,
obligate hemiparasitic shrubs with
branches 15-80 cm. (5.9-31.5 in.) long. Their hosts are woody shrubs and trees. The foliage
is dichotomously or verticillately branching, with opposite pairs or whorls of
green leaves which
perform some
photosynthesis (minimal in some species, notably Viscum 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 flowers
are inconspicuous, greenish-yellow, 1-3 mm. (0.039-0.118 in.) diameter.
The fruit is a
berry, white, yellow, orange, or red when mature, containing one or more
seeds embedded in
very sticky juice; the seeds are dispersed when
birds (notably the
mistle thrush) eat the fruit, and remove the sticky seeds from the bill by
wiping them on tree branches where they can germinate.
Viscum species are poisonous to humans; eating the fruit causes a weak
pulse and acute gastrointestinal problems including stomach pain and
diarrhea.
At least one of the active ingredients is the
lectin
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.
Selected species:
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| Viscum album,
Santalaceae, European Mistletoe, habitus. Arboretum of the
Botanical Garden University Tόbingen, Germany. |
- Viscum album European mistletoe
- Viscum articulatum Burm.f. leafless
mistletoe (Tropical & Subtropical Asia to S. Pacific)
- Viscum bancroftii Blakely
(Queensland, Australia)
- Viscum capense L.f. Cape mistletoe (South Africa)
- Viscum coloratum (Kom.) Nakai Korean mistletoe (Russian
Far East to China and Temp. E. Asia)
- Viscum combreticola
Engl. Combretum mistletoe (Kenya to S.
Africa)
- Viscum cruciatum red-berry mistletoe
(Lebanon, Morocco, Palestine, Portugal, Spain and Syria)
- Viscum diospyrosicola Hayata
(China, Taiwan)
- Viscum exile Barlow (Sulawesi)
- Viscum fargesii Lecomte (E.
Qinghai to Central China)
- Viscum liquidambaricola Hayata (Himalaya
to China and Taiwan)
- Viscum loranthi (Himalya to China,
N.W. India, Sumatra, Philippines)
- Viscum minimum Harv. (S.
Cape Prov.)
- Viscum monoicum Rox. ex DC. (Indian
Subcontinent to China - S. Yunnan, W. Guangxi - and Indo-China)
- Viscum multinerve (Hayata) Hayata (Indian
Subcontinent to China (S. Yunnan, W. Guangxi) and Indo-China)
- Viscum nudum Danser (China:
Sichuan, Yunnan, W. Guizhou)
- Viscum orientale Willd (Afghanistan
to Indian Subcontinent)
- Viscum ovalifolium Wall. ex DC. (Tropical
& Subtropical Asia to N. Australia)
- Viscum rotundifolium
L.f. round-leaved or red-berry
mistletoe (S. DR Congo to S. Africa)
- Viscum scurruloideum Barlow (W.
Jawa)
- Viscum triflorum DC (Sγo
Tomι, Central African Republic to N. Somalia and S. Africa, Arabian
Peninsula, W. Indian Ocean)
- Viscum whitei Blakely (N. &
NE. Australia)
- Viscum yunnanense H.S.Kiu (China
- Yunnan: Mengla)
Cultural references
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