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Johnson grass or Johnsongrass, ''Sorghum halepense'', is a plant in the grass family, Poaceae, native to the Mediterranean region, but grows throughout Europe and the Middle East. The plant has been introduced to all continents except Antarctica, and most larger islands and archipelagos. It reproduces by rhizomes and seeds. Johnson grass has been used for forage and to stop erosion, but it is often considered a weed because: * Foliage that becomes wilted from frost or hot, dry weather can contain sufficient amounts of hydrogen cyanide to kill cattle and horses if it is eaten in quantity. * The foliage can cause 'bloat' in such herbivores from the accumulation of excessive nitrates; otherwise, it is edible. * It grows and spreads so quickly, it can 'choke out' other cash crops planted by farmers. This species occurs in crop fields, pastures, abandoned fields, rights-of-way, forest edges, and along streambanks. It thrives in open, disturbed, rich, bottom ground, particularly in cultivated fields. Johnson grass resistant to the common herbicide glyphosate has been found in Argentina and the United States.〔Western Farm Press. (Johnsongrass resistance to glyphosate confirmed in Argentina ), Aug 28, 2006. (accessed 2010.01.06)〕〔Monsanto. (Glyphosate-resistant Johnsongrass Confirmed in Two Locations ), March 12, 2008. (accessed 2010.01.06)〕〔Delta Farm Press. (Glyphosate-resistant Johnsongrass in Mid-South ), March 19, 2008 (accessed 2010.01.06)〕 It is considered to be one of the ten worst weeds in the world.〔BugwoodWiki() Holm, L. G., P. Donald, J. V. Pancho, and J. P. Herberger. 1977. The World's Worst Weeds: Distribution and Biology. The University Press of Hawaii, Honolulu, Hawaii. 609 pp.〕 It is named after an Alabama plantation owner, Colonel William Johnson, who sowed its seeds on river-bottom farm land ''circa'' 1840. The plant was already established in several US states a decade earlier, having been introduced as a prospective forage or accidentally as a seedlot contaminant.〔(Dept of Soil and Crop Science, Texas A & M University )〕〔(Ohio State Uni. Agricultural Research and Development Center )〕 ==References== 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「Johnson grass」の詳細全文を読む スポンサード リンク
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