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''Phoradendron'' is a genus of mistletoes, native to warm temperate and tropical regions of the Americas. The center of diversity is the Amazon rainforest.〔Coder, K. D. (American mistletoe (''Phoradendron serotinum'' var. ''serotinum'') infection in trees. ) WSFNR08-25. Tree Health Series. University of Georgia. 2008.〕 Traditionally, the genus has been placed in the family Viscaceae, but recent genetic research acknowledged by the Angiosperm Phylogeny Group shows this family to be correctly placed within a larger circumscription of the sandalwood family, Santalaceae. They are woody hemi-parasitic shrubs with branches long, which grow on other trees. The foliage is dichotomously branching, with opposite pairs of leaves; these are fairly large, long, green and photosynthetic in some species (e.g. ''P. leucarpum''), but minimal in some others (e.g. ''P. californicum''). Although they are able to photosynthesize the plant relies on its host for some nutrients. The plant draws its mineral and water needs, and some of its energy needs, from the host tree using a haustorium which grows into the stems of the host.〔Hiller, J. B. (2010). Marvelling at mistletoe. ''Highlights for Children''. 65(12) 40-41.〕 The genus name ''Phoradendron'' is derived from the Greek for "tree thief".〔〔(''Phoradendron''. ) The Jepson Manual eFlora 2012.〕 The flowers are inconspicuous, greenish-yellow, diameter. The fruit is a berry, white, yellow, orange, or red when mature, containing several seeds embedded in very sticky juice. The seeds are dispersed when birds eat the fruit and remove the sticky seeds from their bills by wiping them on tree branches where they can germinate. The foliage and berries of some species are toxic. Leafy mistletoes seldom kill but they cause stress reducing crop productions in fruits and nut trees.〔Krautwurst, T. (2003) The truth about mistletoe. ''Mother Earth News'' 195 26-29.〕 ==Host and symptoms== ''Phoradendron'' species can infest many taxa of plants including hackberry (''Celtis spp.'') mesquite, cedar, elm, and Osage-orange.〔Turner, M. W. ''Remarkable Plants of Texas: Uncommon Accounts of our Common Natives''. University of Texas Press. 2009. pg. 261.〕 Certain species of ''Phoradendron'' are host-specific; for example, in Arizona, ''Phoradendron tomentosum'' infests cottonwood (''Populus fremontii''), sycamore (''Platanus wrightii''), ash (''Fraxinus'' spp.), walnut (''Juglans'' spp.) and willow (''Salix'' spp.).〔Geils, B. W., et al. (Mistletoes of North American conifers. ) Gen. Tech. Rep. RMRS-GTR-98. Ogden, Utah: USDA, Forest Service, Rocky Mountain Research Station. 2002.〕 ''P. californicum'' infests shrubs and trees such as acacia (''Acacia'' spp.) and blue palo verde (''Parkinsonia florida''). Some species infest junipers (''Juniperus'' spp.) and oaks (''Quercus'' spp.).〔Hine, R. (Diseases of Urban Plants. ) Adapted by M. Olsen. Plant Disease Publications. University of Arizona Cooperative Extension. Revised 1999.〕 Branches often become swollen and distorted, forming burls and making the tree more susceptible to insect attack.〔 ''Phoradendron'' presents serious problems along rivers, streams, parks, and golf courses with large cottonwood trees. Deciduous trees can be mistaken for evergreens during the winter if infection is heavy.〔 Other common symptoms include swelling formations of witch's broom, dieback, and weakened branches.〔Call, R. E. (Mistletoe. ) Home Horticulture. University of Arizona Cooperative Extension, Cochise County.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Phoradendron」の詳細全文を読む スポンサード リンク
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