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The Leyland cypress, ''Cupressus'' × ''leylandii'', often referred to simply as leylandii, is a fast-growing coniferous evergreen tree much used in horticulture, primarily for hedges and screens. Even on sites of relatively poor culture, plants have been known to grow to heights of in 16 years. Their rapid, thick growth means they are sometimes used to enforce privacy, but such use can result in disputes with neighbours whose own property becomes overshadowed. ==Taxonomic status of Nootka cypress== The taxonomic status of Nootka cypress has changed over time. In the past, it was regarded as belonging in the genus ''Cupressus'', and later placed in ''Chamaecyparis''. It has become clear, however, that when the genus ''Cupressus'' is defined to include ''Chamaecyparis'', it is paraphyletic unless it also includes ''Juniperus''.〔 In 2004, Little et al. transferred the Nootka cypress to ''Callitropsis''. Little (2006) proposed another alternative by transferring all the North American species of ''Cupressus'', including the Monterey cypress (''C. macrocarpa''), to ''Callitropsis''. In some of these classifications, the hybrids become very unusual in being intergeneric hybrids, the only ones ever reported among the gymnosperms. In 2010, Mao et al. performed a more detailed molecular analysis and redefined ''Cupressus'' to exclude ''Chamaecyparis'', but to include the Nootka cypress. It may be added that attempts to cross Nootka cypress with other ''Chamaecyparis'' species have been universally unsuccessful. Where Nootka cypress is treated in ''Chamaecyparis'', the name of the hybrid becomes ×''Cupressocyparis leylandii'', and where treated in ''Xanthocyparis'', the hybrid becomes ×''Cuprocyparis leylandii''. Two other similar hybrids have also been raised, both involving Nootka cypress with other ''Cupressus'' species: :''Cupressus arizonica'' var. ''glabra'' × ''Cupressus nootkatensis'' (''Cupressus'' × ''notabilis'') :''Cupressus lusitanica'' × ''Cupressus nootkatensis'' (''Cupressus'' × ''ovensii'') 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「Leyland cypress」の詳細全文を読む スポンサード リンク
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