The

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

''Arceuthobium'', commonly called dwarf

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, is a genus of 26 species of

parasitic plant A parasitic plant is a plant that derives some or all of its nutritional requirements from another living plant. They make up about 1% of angiosperms and are found in almost every biome. All parasitic plants develop a specialized organ called the ...

s that parasitize members of

Pinaceae The Pinaceae, or pine family, are conifer trees or shrubs, including many of the well-known conifers of commercial importance such as Cedrus, cedars, firs, Tsuga, hemlocks, larches, pines and spruces. The family is included in the order Pinales, ...

and

Cupressaceae Cupressaceae is a conifer family, the cypress family, with worldwide distribution. The family includes 27–30 genera (17 monotypic), which include the junipers and redwoods, with about 130–140 species in total. They are monoecious, subdio ...

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...

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 ...

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 ...

, and

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 ...

. Of the 42 species that have been recognized, 39 and 21 of these are endemic to North America and the United States, respectively. They all have very reduced shoots and

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 ...

(mostly reduced to scales) with the bulk of the plant living under the host's bark. Recently the number of species within the genus has been reduced to 26 as a result of more detailed genetic analysis.

Description

They are

dioecious Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproductio ...

, individual plants being either male or female. 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 unusual in that it builds up hydrostatic pressure internally when ripe and shoots the single sticky

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 ...

up to speeds nearly , an example of

rapid plant movement Rapid plant movement encompasses plant movements, movement in plant structures occurring over a very short period, usually under one second. For example, the Venus flytrap closes its trap in about 100 milliseconds. The traps of Utricularia are muc ...

. The lodgepole pine dwarf mistletoe,'' Arceuthobium americanum, has been found to explosively-disperse its seeds through

thermogenesis Thermogenesis is the process of heat production in organisms. It occurs in all warm-blooded animals, and also in a few species of thermogenic plants such as the Eastern skunk cabbage, the Voodoo lily (''Sauromatum venosum''), and the giant wate ...

.
Rolena A.J. deBruyn, Mark Paetkau, Kelly A. Ross, David V. Godfrey &

Cynthia Ross Friedman Cynthia "Cindy" Ross Friedman (1970 or 1971 – 24 December 2018) was a professor in biological sciences at Thompson Rivers University in Kamloops, British Columbia, Canada. She was inducted into the inaugural cohort of the Royal Society of Cana ...

. Thermogenesis-triggered seed dispersal in dwarf mistletoe. Dwarf mistletoe seeds are enveloped in a

hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance ...

, glue-like substance called

viscin {{Short pages monitor A standardized system called the Hawksworth 6-class dwarf mistletoe rating (DMR) system has been devised to determine how much dwarf mistletoe has infected a tree. To use this system, the living part of the

tree crown The crown of a plant refers to the total of an individual plant's aboveground parts, including stems, leaves, and reproductive structures. A plant community canopy consists of one or more plant crowns growing in a given area. The crown of a wo ...

needs to be broken up into 3 sections, (top, middle, bottom). Each section is then rated either 0, 1, or 2 with a score of 0 being assigned for a uninfected section, 1 for light infection with fewer than half of the branches infected, or 2 for heavy infection with over half of the branches infected. The 3 numbers are then added together to give the total rating for the tree.

Species

Arceuthobium occidentale on Pinus sabiniana

* '' Arceuthobium abietinum'' Engelm. ex Munz * ''

Arceuthobium americanum ''Arceuthobium americanum'' is a species of dwarf mistletoe known as American dwarf mistletoe and lodgepole-pine dwarf mistletoe. It is a common plant of western North America where it lives in high elevation pine forests. It is a parasitic plant ...

'' Nutt. ex Engelm. * '' Arceuthobium apachecum'' Hawksworth & Wiens * ''

Arceuthobium azoricum ''Arceuthobium azoricum'' (Portuguese: espigos-de-cedro) is a species of dwarf mistletoe endemic to the Azores. The population is restricted to the ''Grupo Central'' (central group) of the archipelago on Faial, Pico, São Jorge and Terceira i ...

'' Hawksw. & Wiens * '' Arceuthobium blumeri'' A. Nels. * '' Arceuthobium californicum'' Hawksworth & Wiens * '' Arceuthobium campylopodum'' Engelm. * '' Arceuthobium cyanocarpum'' (A. Nels. ex Rydb.) A. Nels. * '' Arceuthobium divaricatum'' Engelm. * ''

Arceuthobium douglasii ''Arceuthobium douglasii'' is a species of Arceuthobium, dwarf mistletoe known as Douglas fir dwarf mistletoe. It is native to western North America from British Columbia to Texas to California, where it lives in forest and woodland as a parasiti ...

'' Engelm. * '' Arceuthobium gillii'' Hawksworth & Wiens * ''

Arceuthobium globosum The genus ''Arceuthobium'', commonly called dwarf mistletoes, is a genus of 26 species of parasitic plants that parasitize members of Pinaceae and Cupressaceae in North America, Central America, Asia, Europe, and Africa. Of the 42 species that h ...

'' Hawksw. & Wiens * '' Arceuthobium laricis'' (Piper) St. John * '' Arceuthobium littorum'' Hawksworth, Wiens & Nickrent * '' Arceuthobium microcarpum'' (Engelm.) Hawksworth & Wiens * '' Arceuthobium minutissimum'' Hook. f. * ''

Arceuthobium monticola ''Arceuthobium monticola'' is a species of dwarf mistletoe known as western white pine dwarf mistletoe. It is endemic to the Klamath Mountains of northern California and southern Oregon, where it lives as a parasite on western white pine trees. ...

'' Hawksworth, Wiens & Nickrent * '' Arceuthobium occidentale'' Engelm. * ''

Arceuthobium oxycedri Arceuthobium oxycedri, juniper dwarf mistletoe, is a hemiparasite of the family Santalaceae. It parasitizes members of the genus ''Juniperus'', especially ''Juniperus oxycedrus'' and ''Juniperus communis''. Description The juniper mistletoe is ...

'' (DC.) M.Bieb. * '' Arceuthobium pusillum'' Peck * '' Arceuthobium siskiyouense'' Hawksworth, Wiens & Nickrent * ''

Arceuthobium tsugense The genus ''Arceuthobium'', commonly called dwarf mistletoes, is a genus of 26 species of parasitic plants that parasitize members of Pinaceae and Cupressaceae in North America, Central America, Asia, Europe, and Africa. Of the 42 species tha ...

'' (Rosendahl) G.N. Jones * '' Arceuthobium vaginatum'' (Humb. & Bonpl. ex Willd.) J. Presl (Syn. ''Viscum vaginatum'' Humb. & Bonpl. ex Willd.)

References

External links

Maleshoots of ''A. campylopodum'' in California

Fruiting plant of ''A. campylopodum'' on Pine shoot

PLANTS profile for Arceuthobium (United States) including range maps.

US forest service data about dwarf mistletoes
{{Taxonbar, from=Q244255 Dioecious plants Epiphytes Parasitic plants Santalales genera

Description

Species

References

Further reading

External links