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The Field Elm cultivar ''Ulmus minor'' 'Plotii', commonly known as Lock Elm or Lock's Elm (its vernacular names), Plot's Elm or Plot Elm, is found growing naturally only in England, where it is encountered mainly in the East Midlands, notably around the River Witham in Lincolnshire, in the Trent Valley around Newark on Trent〔Melville, Ronald, ''The Journal of Botany'', London, Vol.78, Aug. 1940〕 and in the village of Laxton, Northamptonshire. It has been described as Britain's rarest native elm, and it is recorded by The Wildlife Trust as a nationally scarce species.〔(Plot’s Elm (Ulmus Plotii) ). Wildlifebcnp.org. Retrieved on 2012-03-22.〕 As with other members of the Field Elm group, the taxonomy of Plot Elm has been a matter of contention, several authorities〔Stace, C. A. (1997). ''New Flora of the British Isles'', 2nd edition. Cambridge University Press.〕 recognizing it as a species in its own right. Indeed, it is as ''U. plotii'' that the specimens held by the Royal Botanic Gardens at Kew and Wakehurst Place are listed. Richens, however, contended (1983) that it is simply one of the more distinctive clones of the polymorphous ''Ulmus minor'', conjecturing that it arose as an ''U. minor'' sport and that its incidence in the English Midlands may have been linked to its use as a distinctive marker along Drovers' roads,〔Richens, R. H., ''Elm'', Cambridge 1983, p.54〕〔Max Coleman, ed.: ''Wych Elm'' (Royal Botanic Garden Edinburgh publication, 2009; ISBN 978-1-906129-21-7); p. 22〕 whereas Melville suggested the tree's distribution may be related to (river) valley systems.〔 After Richens had challenged the species idea, the tree was the subject of a study at the Royal Botanic Garden Edinburgh by Dr Max Coleman (2000), which showed that trees that were a perfect fit with the 'type' material of Plot elm were of a single clone (genetically identical to each other). Arguing in a 2002 paper that there was no clear distinction between species and subspecies, and suggesting that known or suspected clones of ''U. minor'', once cultivated and named, should be treated as cultivars, Coleman preferred the designation ''U. minor'' 'Plotii'.〔Coleman M. (2002) 'British elms.' ''British Wildlife'' 13 (6): 390-395.〕 Henry miscalled the tree Goodyer's Elm. The trees Goodyer discovered (''U. minor'' 'Goodyeri') were near the coast at Pennington, Hampshire, some 200 miles away from their main centre of distribution and very dissimilar in structure.〔Elwes, H. J. & Henry, A. (1913). (''The Trees of Great Britain & Ireland'' ). Vol. VII. pp. 1848–1929. Private publication.〕〔White, J. & More, D. (2002). ''Trees of Britain & Northern Europe''. Cassell's, London.〕〔Chatters, C. (2009) ''Flowers of the Forest – Plants and people of the New Forest National Park''. Wildguides, Old Basing, England. ISBN 978-1-903657-19-5〕 ==Description== Before the advent of Dutch elm disease, this slender monopodial tree grew to a height of 30 m and was chiefly characterized by its cocked crown comprising a few short ascending branches; Richens〔Richens, R. H. (1968). The correct designation of the European field elms. ''Feddes Repertorium'' 79: 1 –2.〕 likened its appearance to an ostrich feather.〔Photograph of young ''U. minor'' var. ''plotii'' in R. H. Richens, ''Elm'' (Cambridge 1983), (p. 4 )〕 A single longish lower branch appears often to have been a feature of its profile.〔See Wilkinson's photo 'Plot Elms finely grown' & 'Young Plot in Trent Valley' (plot-elms.co.uk/home/unknown-location-plot-elms), Druce's Banbury photo (plot-elms.co.uk/home/oxfordshire-plot-elms), Stace's Lowesby photo 3 (plot-elms.co.uk/home/leicestershire-plot-elms), Westonbirt photo, Bruntsfield Links elm, etc.〕 The obovate to elliptic acuminate leaves are small, rarely > 4 cm in length, with comparatively few marginal teeth, usually < 70; the upper surfaces dull, with a scattering of minute tubercles and hairs.〔(Photograph 1 of Plot's Elm leaves, elmer.rbge.org.uk )〕〔(Photograph 2 of Plot's Elm leaves, elmer.rbge.org.uk )〕 The samarae rarely ripen, but when mature are narrowly obovate, < 13 mm in length, with a triangular open notch.〔〔 Image:Ulmus minor 'Plotii'.jpg|'Plotii', Banbury, 1911 (two contiguous trees) Image:Ulmus minor 'Plotii' Laxton Northamptonshire.jpg|Young Plot Elm, Laxton, Northamptonshire, 2015 Image:Plot Elm leaves - Madingley Road, Cambridge.jpg|Plot foliage, Madingley Road, Cambridge Image:Plot's Elm foliage 1.jpg|Juvenile foliage, Laxton Image:Plot elm hedge, Caythorpe, Nottinghamshire.jpg|Plot hedge, Caythorpe, Nottinghamshire 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 minor 'Plotii'」の詳細全文を読む スポンサード リンク
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