Ulmus davidiana var. japonica

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Ulmus davidiana var. japonica
Dai Guang Bao Cun Shu Mu - panoramio.jpg
Ulmus davidiana var. japonica, Obihiro, Hokkaido, Japan
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Rosales
Family: Ulmaceae
Genus: Ulmus
Species:
U. davidiana
Variety:
U. d. var. japonica
Trinomial name
Ulmus davidiana var. japonica
Synonyms
  • Ulmus campestrisKomarov
  • Ulmus campestrisL. var. japonicaRehder
  • Ulmus campestris var. laevisFr. Schmidt
  • Ulmus campestris var. vulgarisShirasawa
  • Ulmus davidiana var. levigata(C. K. Schneid.), Nakai
  • Ulmus davidiana var. japonica f. suberosaNakai
  • Ulmus japonica(Rehder), Sarg.
  • Ulmus japonica var. levigataC. K. Schneid.
  • Ulmus propinquaKoidz.
  • Ulmus wilsonianaC. K. Schneid.

Ulmus davidiana var. japonica, the Japanese elm, is one of the larger and more graceful Asiatic elms, endemic to much of continental northeast Asia and Japan, where it grows in swamp forest on young alluvial soils, although much of this habitat has now been lost to intensive rice cultivation. [1]

Contents

Classification

Some authorities do not consider japonica to be a variety of Ulmus davidiana , The Illustrated Flora of the Primorsky Territory, Russian Far East (2019), for example, maintaining U. japonica as a species. [2] [3]

Description

The size and shape of the Japanese elm is extremely variable, [4] ranging from short and bearing a densely branched broad crown similar to the Wych elm [5] to tall, single-stemmed, with narrow crown similar to the English elm. [6] [7] Augustine Henry described one of the latter outside Iwamigawa, Hokkaido, railway station as being 34 m tall, with a clean stem to a height of approximately 15 m. [8] Takenoshin Nakai distinguished a local cork-barked form, f. suberosa (Flora of Japan, 1965), [9] while Morton Arboretum, Illinois, distinguishes a cork-barked form from China, U. propinqua var. suberosa. [10] [11] A smooth-leaved form, f. kijimae, was originally named U. kijimae. [9] Japanese elm is distinguished by the fawn colour of shoots at the end of their first season, the shoots often being roughened by minute tubercles or 'warts'. [12] [13] [14] [15] The young shoots often bear corky wings, similar to those of the European field elm U. minor, to which it is closely related.

The leaves are generally obovate, < 11 cm long, with a petiole about 10mm long. [16] Like many of the European field elms, var. japonica retains its green foliage well into the autumn, before a late display of deep yellow. Schneider (1907) and Bean noted that the variety from western China, formerly known as U. wilsoniana, [17] has 16 to 22 pairs of leaf-veins, [18] [19] while the eastern type tree has not more than 16. [20] [21] The perfect, apetalous wind-pollinated flowers emerge in early spring, before the leaves. The samara, <15 mm long, is obovate to orbicular, occasionally hairy over its entire surface but more often glabrous, [7] [22] the seed touching the notch, the inner margins of which are ciliate, the stigmas being slightly incurved. [23] [24] Trees grown from seed at Great Fontley in southern England first flowered aged 13 years. [25] The species does not sucker from roots. [7]

Pests and diseases

Natural populations of Japanese elm have a low to moderate resistance to Dutch elm disease. In trials in the Netherlands, susceptibility to disease was found to be commensurate with rate of growth, the more vigorous specimens exhibiting far more foliar damage after inoculation with the causal fungus. [26] Careful selection in North America has produced a number of cultivars highly resistant to disease (see Hybrids, hybrid cultivars and cultivars below). The tree is resistant to the elm leaf beetle Xanthogaleruca luteola [27] but is moderately susceptible to elm yellows. [28]

Cultivation

Japanese elm has been widely planted in northern Japan as a street tree. It was introduced to Arnold Arboretum, Massachusetts, in 1895 as seed sent from Sapporo by Professor Kingo Miyabe, [29] whence two seedlings were donated to Kew Gardens, London, in 1897. [30] The Späth nursery, Berlin, marketed Japanese elm in Europe from 1900, [31] Kew obtaining a third specimen from them in that year. [32] Specimens were supplied by Späth to the Royal Botanic Garden Edinburgh in 1903 as U. campestris japonica [33] and may survive in Edinburgh, as it was the practice of the Garden to distribute trees about the city. [34] A specimen of U. campestris japonica obtained from Späth stood in the Ryston Hall arboretum, Norfolk, [35] in the early 20th century. [36] The Arnold Arboretum specimens grew rapidly, and first flowered aged 12 years. A form from western China, for many years distinguished as U. wilsonianaSchneider, was introduced to the Arnold Arboretum in 1910. The Morton Arboretum, Illinois, has intermediate forms labelled U. japonica × U. wilsoniana. [37] [38] Unlike many Asiatic species, Japanese elm is tolerant of a mild, maritime climate with heavy winter rainfall and was consequently considered of potential use in the Dutch elm breeding programme led by H. M. Heybroek at the Dorschkamp Research Institute at Wageningen. [26] In 1977, Heybroek collected the tree in Japan, with the result that there is now a small forest of Japanese elm in southern Flevoland, the largest plantation of the species beyond its native land. [39]

The tree was briefly propagated and marketed in the UK by the Hillier & Sons nursery, Winchester, Hampshire from 1971 to 1977. [40] [41] Specimens planted at the Sir Harold Hillier Gardens have grown very well on heavy clay in an open location, where they support colonies of the White-letter Hairstreak Satyrium w-album . In trials elsewhere in Hampshire conducted by Butterfly Conservation , the tree also proved tolerant of dry soils on chalk and soils waterlogged in winter, although growth has been comparatively slow and leaves are late to flush, rarely before mid-May. [25]

Leaves from the tree were eaten during the Great Chinese Famine, but found to cause facial swelling. [42]

Notable trees

In the UK, the TROBI Champion grows at the Royal Horticultural Society's Rosemoor garden in Devon, measuring 16 m tall in 2017. Another large tree grows at the Sir Harold Hillier Gardens, Romsey, measuring 13 m tall by 42 cm d.b.h. in 2003. A large specimen grows at Sussex University, Falmer, Brighton, but may be the cultivar 'Jacan'. [44] The oldest putative specimen in Edinburgh, possibly one of those supplied as U. campestris japonica by Späth in 1903, [34] had a bole-girth of about 3.5 m (felled 2018). [45] [46] [47]

Cultivars

Japanese elm was assessed in Canada as a substitute for native elms which had succumbed to Dutch elm disease. Six particularly hardy cultivars were released there in the 1980s; three were also raised in the United States : 'Discovery', 'JFS-Bieberich' = Emerald Sunshine (formerly treated under U. propinquaKoidz.), 'Freedom', 'Jacan', 'Mitsui Centennial', 'Prospector' (formerly treated under Wilson's elm U. wilsoniana C.K. Schneid.), 'Reseda', 'Thomson', Validation [48] However, most of the Canadian clones have now been withdrawn from commerce owing to the Canadian government's restrictions on the movement of elm within the country, adopted to prevent the spread of Dutch elm disease.

Hybrids and hybrid cultivars

The hybrid Ulmus davidiana var. japonica × U. minor was raised at the Arnold Arboretum before 1924. [50]

The Japanese elm was widely used in the US in hybridization experiments at the Morton Arboretum and University of Wisconsin, [51] [52] resulting in the release of the following cultivars: 'Cathedral', 'Morton' = Accolade, 'Morton Glossy' = Triumph, 'Morton Plainsman' = Vanguard, 'Morton Red Tip' = Danada Charm, 'Morton Stalwart' = Commendation, 'New Horizon', 'Patriot', 'Rebona', 'Repura', 'Revera', and 'Sapporo Autumn Gold'.

The species has also been crossed with Dutch hybrids by the Istituto per la Protezione delle Piante (IPP) in Florence, Italy. Two clones, 'FL 610' and 'FL 626' were evaluated in England, by Butterfly Conservation . [25]

Accessions

North America
Europe

Nurseries

North America
Europe

Related Research Articles

<i>Ulmus laciniata</i> Species of tree

Ulmus laciniata(Trautv.) Mayr, known variously as the Manchurian, cut-leaf, or lobed elm, is a deciduous tree native to the humid ravine forests of Japan, Korea, northern China, eastern Siberia and Sakhalin, growing alongside Cercidiphyllum japonicum, Aesculus turbinata, and Pterocarya rhoifolia, at elevations of 700–2200 m, though sometimes lower in more northern latitudes, notably in Hokkaido.

<i>Ulmus macrocarpa</i> Species of tree

Ulmus macrocarpaHance, the large-fruited elm, is a deciduous tree or large shrub endemic to the Far East excluding Japan. It is notable for its tolerance of drought and extreme cold and is the predominant vegetation on the dunes of the Khorchin sandy lands in the Jilin province of north-eastern China, making a small tree at the base of the dunes, and a shrub at the top.

<i>Ulmus davidiana</i> Species of tree

Ulmus davidiana, also known as the David elm, or Father David elm, is a small deciduous tree widely distributed across China, Mongolia, Korea, Siberia, and Japan, where it is found in wetlands along streams at elevations of 2000–2300 m (6,500–7,500 ft). The tree was first described in 1873 from the hills north of Beijing, China.

Ulmus pseudopropinquaWang & Li, occasionally known in the United States as the Harbin spring elm, is a small deciduous tree found only in Heilongjiang, the northeasternmost province in China. The tree has not been studied comprehensively, and it has been speculated it may be a natural hybrid of Ulmus davidiana var. japonica and Ulmus macrocarpa.

<i>Ulmus minor</i> Stricta Elm cultivar

The field elm cultivar Ulmus minor 'Stricta', known as Cornish elm, was commonly found in South West England, Brittany, and south-west Ireland, until the arrival of Dutch elm disease in the late 1960s. The origin of Cornish elm in the south-west of Britain remains a matter of contention. It is commonly assumed to have been introduced from Brittany. It is also considered possible that the tree may have survived the ice ages on lands to the south of Cornwall long since lost to the sea. Henry thought it "probably native in the south of Ireland". Dr Max Coleman of Royal Botanic Garden Edinburgh, arguing in his 2002 paper on British elms that there was no clear distinction between species and subspecies, suggested that known or suspected clones of Ulmus minor, once cultivated and named, should be treated as cultivars, preferred the designation U. minor 'Stricta' to Ulmus minor var. stricta. The DNA of 'Stricta' has been investigated and the cultivar is now known to be a clone.

<i>Ulmus</i> × <i>hollandica</i> Belgica Elm cultivar

The hybrid elm cultivar Ulmus × hollandica 'Belgica', one of a number of hybrids arising from the crossing of Wych Elm with a variety of Field Elm, was reputedly raised in the nurseries of the Abbey of the Dunes, Veurne, in 1694. Popular throughout Belgium and the Netherlands in the 19th century both as an ornamental and as a shelter-belt tree, it was the 'Hollandse iep' in these countries, as distinct from the tree known as 'Dutch Elm' in Great Britain and Ireland since the 17th century: Ulmus × hollandica 'Major'. In Francophone Belgium it was known as orme gras de Malines.

<i>Ulmus</i> × <i>hollandica</i> Dampieri Elm cultivar

The hybrid elm cultivar Ulmus × hollandica 'Dampieri', one of a number of cultivars arising from the crossing of the Wych Elm U. glabra with a variety of Field Elm U. minor, is believed to have originated in continental Europe. It was marketed in Wetteren, Belgium, in 1851 as 'Orme de Dampier', then in the Low Countries in 1853, and later identified as Ulmus campestris var. nuda subvar. fastigiata DampieriHort., Vilv. by Wesmael (1862).

<i>Ulmus</i> Morton Elm cultivar

Ulmus 'Morton' is an elm cultivar cloned from a putative intraspecific hybrid planted at the Morton Arboretum in 1924, which itself originated as seed collected from a tree at the Arnold Arboretum in Massachusetts. Although this tree was originally identified as Ulmus crassifolia, it is now believed to have been a hybrid of the Japanese elm and Wilson's elm. Accolade has proven to be the most successful cultivar tested in the US National Elm Trial, averaging a survival rate of 92.5% overall.

<i>Ulmus</i> Exoniensis Elm cultivar

Ulmus 'Exoniensis', the Exeter elm, was discovered near Exeter, England, in 1826, and propagated by the Ford & Please nursery in that city. Traditionally believed to be a cultivar of the Wych Elm U. glabra, its fastigiate shape when young, upward-curving tracery, small samarae and leaves, late leaf-flush and late leaf-fall, taken with its south-west England provenance, suggest a link with the Cornish Elm, which shares these characteristics. The seed, however, is on the stalk side of the samara, a feature of wych elm and its cultivars, whereas in hybrids it would be displaced towards the notch.

<i>Ulmus glabra</i> Cornuta Elm cultivar

The Wych Elm cultivar Ulmus glabra 'Cornuta', in cultivation before 1845 – Fontaine (1968) gives its provenance as France, 1835 – is a little-known tree, finally identified as a cultivar of U. glabra by Boom in Nederlandse Dendrologie 1: 157, 1959.

<i>Ulmus davidiana</i> var. <i>japonica</i> Prospector Elm cultivar

The Japanese elm cultivar Ulmus davidianavar.japonica 'Prospector' was originally treated as a cultivar of Wilson's elm U. wilsonianaSchneid., a species sunk as Ulmus davidiana var. japonica by Fu. A U.S. National Arboretum introduction, it was selected in 1975 from a batch of 1965 seedlings in Delaware, Ohio, and released without patent restrictions in 1990. 'Prospector' proved moderately successful in the US National Elm Trial, averaging a survival rate of 76% overall.

<i>Ulmus</i> Patriot Elm cultivar

Ulmus 'Patriot' is a hybrid cultivar raised by the United States National Arboretum in 1980. Derived from a crossing of the American hybrid 'Urban' with the Wilson's Elm cultivar 'Prospector', 'Patriot' was released to commerce, free of patent restrictions, in 1993. Tested in the US National Elm Trial coordinated by Colorado State University, 'Patriot' averaged a survival rate of 85% after 10 years.

<i>Ulmus minor</i> Propendens Elm cultivar

The Field Elm cultivar Ulmus minor 'Propendens', described by Schneider in 1904 as U. glabra (:minor) var. suberosa propendens, Weeping Cork-barked elm, was said by Krüssmann (1976) to be synonymous with the U. suberosa pendula listed by Lavallée without description in 1877. Earlier still, Loudon's Arboretum et Fruticetum Britannicum had included an illustration of a pendulous "cork-barked field elm", U. campestris suberosa. An U. campestris suberosa pendula was in nurseries by the 1870s.

<i>Ulmus laciniata <span style="font-style:normal;">var.</span> nikkoensis</i> Variety of tree

Ulmus laciniata var. nikkoensisRehder, the Nikko elm, was discovered as a seedling near Lake Chūzenji, near Nikkō, Japan, and obtained by the Arnold Arboretum in 1905. The taxonomy of the tree remains a matter of contention, and has been considered possibly a hybrid of U. laciniata and U. davidiana var. japonica. However, in crossability experiments at the Arnold Arboretum in the 1970s, U. laciniata, a protogynous species, was found to be incompatible with U. davidiana var. japonica, which is protandrous.

<i>Ulmus pumila</i> Pinnato-ramosa Elm cultivar

The Siberian elm cultivar Ulmus pumila 'Pinnato-ramosa' was raised by Georg Dieck, as Ulmus pinnato-ramosa, at the National Arboretum, Zöschen, Germany, from seed collected for him circa 1890 in the Ili valley, Turkestan by the lawyer and amateur naturalist Vladislav E. Niedzwiecki while in exile there. Litvinov (1908) treated it as a variety of Siberian elm, U. pumilavar.arborea but this taxon was ultimately rejected by Green, who sank the tree as a cultivar: "in modern terms, it does not warrant recognition at this rank but is a variant of U. pumila maintained and known only in cultivation, and therefore best treated as a cultivar". Herbarium specimens confirm that trees in cultivation in the 20th century as U. pumilaL. var. arboreaLitv. were no different from 'Pinnato-ramosa'.

<i>Ulmus parvifolia</i> Species of tree

Ulmus parvifolia, commonly known as the Chinese elm or lacebark elm, is a species native to eastern Asia, including China, India, Japan, Korea, and Vietnam. It has been described as "one of the most splendid elms, having the poise of a graceful Nothofagus".

Ulmus×mesocarpaM. Kim & S. Lee is a natural hybrid elm which is a cross of Ulmus macrocarpa with Japanese elm Ulmus davidiana var. japonica discovered on Seoraksan near the city of Sokcho on the eastern coast of South Korea. The tree is endemic to the provinces of Gangwon-do, Injegun, Bukmyeon, Yongdaeri, and Baekdamsa.

<i>Ulmus minor</i> Suberosa Elm cultivar

The Field Elm cultivar Ulmus minor 'Suberosa', commonly known as the Cork-barked elm, is a slow-growing or dwarf form of conspicuously suberose Field Elm. Of disputed status, it is considered a distinct variety by some botanists, among them Henry (1913), Krüssmann (1984), and Bean (1988), and is sometimes cloned and planted as a cultivar. Henry said the tree "appears to be a common variety in the forests of central Europe", Bean noting that it "occurs in dry habitats". By the proposed rule that known or suspected clones of U. minor, once cultivated and named, should be treated as cultivars, the tree would be designated U. minor 'Suberosa'. The Späth nursery of Berlin distributed an U. campestris suberosa alataKirchn. [:'corky-winged'] from the 1890s to the 1930s.

The elm cultivar Ulmus 'Turkestanica' was first described by Regel as U. turkestanica in Dieck, Hauptcat. Baumschul. Zöschen (1883) and in Gartenflora (1884). Regel himself stressed that "U. turkestanica was only a preliminary name given by me; I regard this as a form of U. suberosa" [:U. minor ]. Litvinov considered U. turkestanicaRegel a variety of his U. densa, adding that its fruits were "like those of U. foliaceaGilibert" [:U. minor].

References

  1. ↑ Makita, H., Miyagi, T., Miura, O., and Kikuchi, T. (1979). A study of an alder forest and an elm forest with special reference to their geomorphological conditions in a small tributary basin. In: Vegetation und Lansdschaft Japans. Bull: Yokohama Phytosoc. Soc. Japan 16, 1979
  2. ↑ Kozhevnikov, Andrey E.; Kozhevnikova Zoya V.; Kwak, Myounghai; Lee, Byoung Yoon (2019), Illustrated Flora of the Primorsky Territory (Russian Far East), National Institute of Biological Resources, Incheon, South Korea
  3. ↑ Ulmus japonica (Rehder) Sarg., Plants of the World Online
  4. ↑ U. japonicaSarg. in Charles Sprague Sargent, ed., Plantae Wilsonianae: an enumeration of the woody plants collected in western China for the Arnold Arboretum of Harvard University during the years 1907, 1908, and 1910 by E. H. Wilson, Vol.3, p.258-261 (Cambridge, Mass., 1916)
  5. ↑ T. H., Everett (1969). "Living trees of the world" (PDF). Thames and Hudson.
  6. ↑ F. K., Makins (1967). The Identification of Trees & Shrubs. Dent. OCLC   500545778.
  7. 1 2 3 Heybroek, Hans M. (1981). "The Japanese elm species and their value for the Dutch elm breeding program" (PDF). Proceedings of the Dutch Elm Disease Symposium and Workshop, October 5–9, Winnipeg, Manitoba: 78–90.
  8. ↑ Elwes, H. J. & Henry, A. (1913). The Trees of Great Britain & Ireland . Vol. VII. 1848–1929. Republished 2014 Cambridge University Press, ISBN   9781108069380
  9. 1 2 Ohwi, Jisaburo (1905-1977); eds. Meyer, Frederick G., and Walker, Egbert H., Flora of Japan (in English) (Washington, D.C., 1965), p.381
  10. ↑ U. propinqua var. suberosa, Morton Arboretum; cirrusimage.com
  11. ↑ Photographs labelled U. japonica var. suberosa on Plant Photo Bank of China, ppbc.iplant
  12. ↑ Elwes and Henry (1913), p.1923
  13. ↑ Bean, W. J. (1988) Trees and shrubs hardy in Great Britain, 8th edition, Murray, London
  14. ↑ Krüssman, Gerd, Manual of Cultivated Broad-Leaved Trees & Shrubs (1984 vol. 3)
  15. ↑ Photograph of fawn-coloured japonica shoot with tubercles or warts; inaturalist.ca
  16. ↑ Hishiyama, C. (Ed.). (2018). A picture book of (Japanese) trees,  p.79. (in Japanese). Seibidoshuppan, Japan. ISBN   9784415310183
  17. ↑ U. wilsonianaSchneider in Charles Sprague Sargent, ed., Plantae Wilsonianae: an enumeration of the woody plants collected in western China for the Arnold Arboretum of Harvard University during the years 1907, 1908, and 1910 by E. H. Wilson, Vol.3, p.238-240 and p.256-257 (Cambridge, Mass., 1916)
  18. ↑ U. wilsoniana leaf and fruit illustrations in Schneider, Camillo Karl, Illustriertes Handbuch der Laubholzkunde (Jena, 1907), p.903-904
  19. ↑ "Ulmus wilsoniana var. wilsoniana". Herbarium catalogue. Royal Botanic Gardens, Kew. Retrieved 17 October 2016. From Chanyang, W. China (Wilson specimen, 1909); "Ulmus wilsoniana var. psilophylla". Herbarium catalogue. Royal Botanic Gardens, Kew. Retrieved 17 October 2016. From Hupeh, C. China (Wilson specimen, 1907); "Ulmus wilsoniana var. subhirsuta". Herbarium catalogue. Royal Botanic Gardens, Kew. Retrieved 17 October 2016. From Szechuan, C. China (Schneider specimen, 1914)
  20. ↑ U. wilsoniana description in Schneider, Camillo Karl, Illustriertes Handbuch der Laubholzkunde (Jena, 1907), p.902
  21. ↑ Bean, W. J., 1988
  22. ↑ Fu, L., Xin, Y. & Whittemore, A. (2002). Ulmaceae, in Wu, Z. & Raven, P. (eds) Flora of China, Vol. 5 (Ulmaceae through Basellaceae). Science Press, Beijing, and Missouri Botanical Garden Press, St. Louis, USA
  23. ↑ Bean (1988), Krüssman (1983)
  24. ↑ "Herbarium specimen - U.1753515". Botany catalogues. Naturalis Biodiversity Center. Sheet labelled U. davidianaPlanch. var. japonica(Rehd.), Hokkaido specimen (new leaves and samarae), 1978
  25. 1 2 3 Brookes, A. H. (2020). Great Fontley Elm Trial, 2020 Report. Butterfly Conservation, Lulworth, England.
  26. 1 2 Heybroek, Hans M. (1983). Burdekin, D.A. (ed.). "Resistant elms for Europe" (PDF). Forestry Commission Bulletin (Research on Dutch Elm Disease in Europe) (60). London: HMSO: 108–113.
  27. ↑ "Elm Leaf Beetle Survey". Archived from the original on 2011-07-19. Retrieved 17 July 2017.
  28. ↑ Mittempergher, L; Santini, A (2004). "The history of elm breeding" (PDF). Investigacion Agraria: Sistemas y Recursos Forestales. 13 (1): 161–177.
  29. ↑ Elwes, H. J. & Henry, A. (1913). The Trees of Great Britain & Ireland. Vol. VII., p.1924 Republished 2004 Cambridge University Press
  30. ↑ W. J., Bean (1981). Trees and shrubs hardy in Great Britain, 7th edition. Murray, London. ISBN   117278583X.
  31. ↑ Späth Catalogue No.106, p.124 (1900-1901)
  32. ↑ Elwes and Henry (1913), p.1924
  33. ↑ "Herbarium specimen - E00824741". Herbarium Catalogue. Royal Botanic Garden Edinburgh. Sheet described as U. campestris japonica, RBGE specimen from Späth nursery, 1903
  34. 1 2 RBGE Cultivated Herbarium Accessions Book: Oct. 1958 notes by Ronald Melville on specimen C2698
  35. ↑ rystonhall.co.uk/
  36. ↑ Ryston Hall Arboretum catalogue. c. 1920. pp. 13–14.
  37. ↑ U. japonica × U. wilsoniana, Morton Arboretum, cirrusimage.com
  38. ↑ U. japonica × U. wilsoniana, Morton Arboretum, acc. no. 495-64, vplants.org
  39. ↑ 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. Photograph of Japanese elm in the Netherlands
  40. ↑ Hillier & Sons (1977). Catalogue of Trees & Shrubs. Hillier, Ampfield, UK.
  41. ↑ Hillier & Sons Sales inventory 1962 to 1977 (unpublished).
  42. ↑ Baranov, A .L. (1962). On the economic use of wild plants in N. E. China. Quarterly Journal of the Taiwan Museum, 15 (122), 1962, 107–115.
  43. ↑ Labelled 'Forest Elms' by photographer (663highland) on Hokkaido University page
  44. ↑ Johnson, O. (2011). Champion Trees of Britain & Ireland,  p.168. Kew Publishing, Kew, London. ISBN   9781842464526.
  45. ↑ Tree labelled Japanese elm by 'Friends of the Meadows and Bruntsfield Links', in Coronation Walk, The Meadows, Edinburgh: fombl.org.uk
  46. ↑ Putative Japanese elm, Coronation Walk, The Meadows, Edinburgh, 1989
  47. ↑ Bark of putative Japanese elm, Coronation Walk, The Meadows, Edinburgh, 1989
  48. ↑ Burdekin, D.A.; Rushforth, K.D. (November 1996). "Elms resistant to Dutch elm disease" (PDF). Arboriculture Research Note. 2/96. Revised by J.F. Webber. Alice Holt Lodge, Farnham: Arboricultural Advisory & Information Service: 1–9. ISSN   1362-5128 . Retrieved 26 October 2017.
  49. ↑ Kim, M., & Lee, S. (1989). Korean J. Pl. Taxon. 19(1) (1989)
  50. ↑ The Morton Arboretum Living Collection, Ulmus list, quercus.mortonarb.org
  51. ↑ Santamour, J., Frank, S. & Bentz, S. (1995). Updated checklist of elm (Ulmus) cultivars for use in North America. Journal of Arboriculture, 21:3 (May 1995), 121-131. International Society of Arboriculture, Champaign, Illinois, US
  52. ↑ Smalley, E. B. & Guries, R. P. (1993). Breeding Elms for Resistance to Dutch Elm Disease. Annual Review of Phytopathology Vol. 31 : 325-354. Palo Alto, California
  53. ↑ "List of plants in the {elm} collection". Brighton & Hove City Council. Retrieved 23 September 2016.
  54. ↑ Royal Botanic Garden Edinburgh, Catalogue of the Living Collections, data.rbge.org.uk; Ulmus daviana var. japonica at RBG Benmore. Acc. no. 19031053; re-propagation from Späth nursery's U. campestris japonica, sent to RBGE 1903.
  55. ↑ Photograph of RBG Benmore's U. japonica (2017); Internation Dendrology Society, Trees and Shrubs online, U. japonica; treesandshrubsonline.org
  56. ↑ Photograph of RHS Rosemoor's U. japonica (2017); Internation Dendrology Society, Trees and Shrubs online, U. japonica; treesandshrubsonline.org
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