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''Ulmus × hollandica'' Mill. , often known simply as Dutch Elm, is a natural hybrid between Wych Elm ''Ulmus glabra'' and Field Elm ''Ulmus minor'' which commonly occurs across Europe wherever the ranges of the two parent species overlap. In England, according to the field-studies of R. H. Richens,〔Richens, R. H., ''Elm'' (Cambridge 1983), p. 95, 233〕 "The largest area (hybridization ) is a band extending across Essex from the Hertfordshire border to southern Suffolk. The next largest is in northern Bedfordshire and adjoining parts of Northamptonshire. Comparable zones occur in Picardy and Cotentin in northern France". F1 hybrids between Wych and Field Elm are fully fertile, but produce widely variant progeny.〔Richens, R. H. (1983), ''Elm''〕 Many also inherit the suckering habit of their Field Elm parent.〔Clouston, Brian, & Stansfield, Kathy, eds.: ''After the Elm'' (Heinemann, London, 1979)〕 Both Richens and Rackham noted that examples in the East Anglian hybridization zone were sometimes pendulous in form.〔〔Oliver Rackham, ''A History of the Countryside'' (London, 1986)〕 A surviving mature ''U. × hollandica'' at Actons Farm, Sawbridgeworth, Hertfordshire - if it was not, as has been suggested, a seedling of Vegeta (Huntingdon Elm) from the local Rivers Nursery (see under Vegeta) - is a case in point. ''U. × hollandica'' hybrids, natural and artificial, have been widely planted elsewhere by man.〔〔Bean, W. J. (1981). ''Trees and shrubs hardy in Great Britain'', 7th edition. Murray, London〕〔Elwes, H. J. & Henry, A. (1913). ''The Trees of Great Britain & Ireland.'' Vol. VII. pp 1848-1929. Private publication, Edinburgh.〕 ==Description== In form and foliage, the trees are broadly intermediate between the two species.〔 Collin, E. (2001). Elm. In Teissier du Cros (Ed.) (2001) ''Forest Genetic Resources Management and Conservation. France as a case study''. Ministry of Agriculture and Fisheries, Bureau of Genetic Resources. INRA DIC. France.〕 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「Ulmus × hollandica」の詳細全文を読む スポンサード リンク
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