The genus ''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 plants that parasitize members of Pinaceae 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, Asia, Europe, and Africa. 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 is unusual in that it builds up hydrostatic pressure internally when ripe and shoots the single sticky seed 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.
Rolena A.J. deBruyn, Mark Paetkau, Kelly A. Ross, David V. Godfrey & Cynthia Ross Friedman. Thermogenesis-triggered seed dispersal in dwarf mistletoe. Dwarf mistletoe seeds are enveloped in a hygroscopic, 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 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 ''Arceuthobium abietinum'' is a species of dwarf mistletoe known as fir dwarf mistletoe. It is native to western North America from Washington to New Mexico to northern Mexico, where it lives in coniferous forests as a parasite on various species ...

'' Engelm. ex Munz * '' Arceuthobium americanum'' Nutt. ex Engelm. * ''

Arceuthobium apachecum ''Arceuthobium apachecum'', called the "Apache dwarf mistletoe," is a parasitic plant found on the branches of pine trees in Arizona, New Mexico and Coahuila Coahuila (), formally Coahuila de Zaragoza (), officially the Free and Sovereign ...

'' 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 ...

'' Hawksw. & Wiens * ''

Arceuthobium blumeri 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 ...

'' A. Nels. * '' Arceuthobium californicum'' Hawksworth & Wiens * ''

Arceuthobium campylopodum ''Arceuthobium campylopodum'' is a species of dwarf mistletoe known as western dwarf mistletoe. It is native to the low to moderate elevation coniferous forests of western North America. It is a common parasite of several species of pine tree, in ...

'' Engelm. * '' Arceuthobium cyanocarpum'' (A. Nels. ex Rydb.) A. Nels. * ''

Arceuthobium divaricatum ''Arceuthobium divaricatum'' is a species of dwarf mistletoe known as pinyon dwarf mistletoe. It is native to the southwestern United States and Baja California, where it lives in woodlands as a parasite on various species of pine, particularly C ...

'' Engelm. * ''

Arceuthobium douglasii ''Arceuthobium douglasii'' is a species of 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 parasite. It is found ...

'' Engelm. * ''

Arceuthobium gillii ''Arceuthobium gillii'', common name "Chihuahua pine dwarf mistletoe," is a parasitic plant found in Arizona, New Mexico, Chihuahua, Sonora and Sinaloa. It is found mostly on the Chihuahua pine ''Pinus leiophylla'', commonly known as Chihuah ...

'' Hawksworth & Wiens * '' Arceuthobium globosum'' Hawksw. & Wiens * ''

Arceuthobium laricis 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 ...

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

Arceuthobium occidentale 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 ...

'' Engelm. * ''

Arceuthobium oxycedri Arceuthobium oxycedr