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''Ulmus minor'' Mill., the Field Elm, is by far the most polymorphic of the European species, although its taxonomy remains a matter of contention. Its natural range is predominantly south European, extending to Asia Minor and Iran; its northern outposts are the Baltic islands of Öland and Gotland,〔(''Ulmus minor'' in Gotland, Sweden: ulmen-handbuch.de/handbuch/ulmus )〕 although it may have been introduced here by man. The tree's typical habitat is low-lying forest along the main rivers, growing in association with oak and ash, where it tolerates summer floods as well as droughts.〔Heybroek, H. M., Goudzwaard, L, Kaljee, H. (2009). ''Iep of olm, karakterboom van de Lage Landen'' (:Elm, a tree with character of the Low Countries). KNNV, Uitgeverij. ISBN 9789050112819〕 Current treatment of the species owes much to Richens,〔Richens, R. H. (1968). The correct designation of the European field elms. ''Feddes Repertorium'' 79: 1-2.〕 who noted (1983) that several varieties of Field Elm are distinguishable on the European mainland. Of these, he listed the small-leaved ''U. minor'' of France and Spain; the narrow-leaved ''U. minor'' of northern and central Italy; the densely hairy leaved ''U. minor'' of southern Italy and Greece; the ''U. minor'' with small-toothed leaves from the Balkans; the ''U. minor'' with large-toothed leaves from the Danube region; and the small-leaved ''U. minor'' from southern Russia and the Ukraine.〔Richens, R. H., ''Elm'' (Cambridge 1983), p.18〕 As for British varieties, "the continental populations most closely related" to eastern English Field Elm "are in central Europe", while south-western forms were introduced from France.〔Richens, R. H., ''Elm'' (Cambridge 1983), p.21〕 He concluded, however, that owing to incomplete field-research at the time of writing, it was "not possible to present an overall breakdown of the European Field Elm into regional varieties".〔Richens, R. H., ''Elm'' (Cambridge 1983), p.88〕 Richens sank a number of British elms, notably English Elm, as either subspecies or varieties of ''U. minor'' in 1968. However, Melville,〔Melville, R. (1978). On the discrimination of species in hybrid swarms with special reference to ''Ulmus'' and the nomenclature of ''U. minor'' (Mill.) and ''U. carpinifolia'' (Gled.). ''Taxon'' 27: 345–351.〕 writing ten years later, identified five distinct species (including ''U. glabra'' in the count), several varieties and numerous complex hybrids. In 1992 Armstrong 〔Armstrong, J. V. & Sell, P. D. (1996). A revision of the British elms (''Ulmus'' L., Ulmaceae): the historical background. ''Bot. J. Linn. Soc.'' 120: 39–50.〕 identified no fewer than forty British species and microspecies. Stace (1997) wrote of the British elms "The two-species (''glabra'' and ''minor'') concept of Richens is not sufficiently discriminating to be of taxonomic value". Nevertheless, it is Richens’ classification which has been the most commonly adopted in recent years, although it is not used in ''Flora Europaea'' ().〔Stace, C. A. (1997). ''New Flora of the British Isles''. 2nd edition. Cambridge University Press.〕 In 2009 Dr Max Coleman of the Royal Botanic Garden, Edinburgh wrote: "The advent of DNA fingerprinting has shed considerable light on the question. A number of studies have now shown that the distinctive forms Melville elevated to species and Richens lumped together as field elm are single clones, all genetically identical, which have been propagated by vegetative means such as cuttings or root suckers. This means that enigmatic British elms such as Plot Elm and English Elm have been shown to be single clones of Field Elm. Although Richens did not have the evidence to prove it, he was correct in recognising a series of clones and grouping them together as a variable species." 〔Max Coleman, ed.: ''Wych Elm'' (Royal Botanic Garden Edinburgh publication, 2009; ISBN 978-1-906129-21-7); p. 22〕 It is hoped that analysis of molecular markers will ultimately eliminate the taxonomic confusion. ==Description== The tree typically grows to < 30 m (98 ft) and bears a rounded crown.〔Photographs of ''Ulmus minor'' in France (L’orme de Martailly-lès-Brancion), krapooarboricole.wordpress.com () ; in Portugal, 1.bp.blogspot.com ().〕 The bark of the trunk is rough, furrowed lightly in older trees to form a block pattern. Young branchlets occasionally have corky wings. The shoots are slender compared with those of wych elm. The leaves are smaller than those of the other European species, hence the specific epithet ''minor'', however they can vary greatly according to the maturity of the tree. Leaves on juvenile growth (suckers, seedlings etc.) are coarse and pubescent, whereas those on mature growth are generally smooth, though remaining highly variable in form; there are generally fewer than 12 pairs of side veins. A common characteristic is the presence of minute black glands along the leaf veins, detectable with the aid of a magnifying glass.〔 The samarae are typically ovate and notched, the notch extending to the central seed. The species readily produces suckers from roots and stumps, even after devastation by Dutch elm disease; consequently genetic resources are not considered endangered (). Image:Ulmus-minor-foliage-mosaic.JPG|''U. minor'' foliage Image:U. minor leaf.jpg|Leaf and 1 Euro coin Image:Ulmus minor 14.jpg|Root-suckers spreading around a Field Elm File:Ulmus minor MHNT.BOT.2010.12.3.jpg|Ulmus minor - MHNT File:Ulmus minor Stapleford bark.jpg|Bark of Stapleford Elm, UK File:Ulmus minor ex Provence flower.jpg|''Ulmus minor'' flower 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」の詳細全文を読む スポンサード リンク
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