Ulmus davidiana var. japonica

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.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 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.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 KoreaUlmus japonica (Rehder) Sarg., Plants of the World Online

Description The size and shape of the Japanese elm is extremely variable,U. japonica Sarg. 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) ranging from short and bearing a densely branched broad crown similar to the Wych elm to tall, single-stemmed, with narrow crown similar to the English elm. 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.Elwes, H. J. & Henry, A. (1913). The Trees of Great Britain & Ireland . Vol. VII. 1848–1929. Republished 2014 Cambridge University Press, Takenoshin Nakai distinguished a local cork-barked form, f. suberosa (Flora of Japan, 1965),Ohwi, Jisaburo (1905-1977); eds. Meyer, Frederick G., and Walker, Egbert H., Flora of Japan (in English) (Washington, D.C., 1965), p.381 while Morton Arboretum, Illinois, distinguishes a cork-barked form from China, U. propinqua var. suberosa. U. propinqua var. suberosa, Morton Arboretum; cirrusimage.comPhotographs labelled U. japonica var. suberosa on Plant Photo Bank of China, ppbc.iplant A smooth-leaved form, f. kijimae, was originally named U. kijimae. 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'.Elwes and Henry (1913), p.1923Bean, W. J. (1988) Trees and shrubs hardy in Great Britain, 8th edition, Murray, LondonKrüssman, Gerd, Manual of Cultivated Broad-Leaved Trees & Shrubs (1984 vol. 3)Photograph of fawn-coloured japonica shoot with tubercles or warts; inaturalist.ca 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. Hishiyama, C. (Ed.). (2018). A picture book of (Japanese) trees,  p.79. (in Japanese). Seibidoshuppan, Japan. 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,U. wilsoniana Schneider 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) has 16 to 22 pairs of leaf-veins,U. wilsoniana leaf and fruit illustrations in Schneider, Camillo Karl, Illustriertes Handbuch der Laubholzkunde (Jena, 1907), p.903-904 From Chanyang, W. China (Wilson specimen, 1909); From Hupeh, C. China (Wilson specimen, 1907); From Szechuan, C. China (Schneider specimen, 1914) while the eastern type tree has not more than 16.U. wilsoniana description in Schneider, Camillo Karl, Illustriertes Handbuch der Laubholzkunde (Jena, 1907), p.902Bean, W. J., 1988 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,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 the seed touching the notch, the inner margins of which are ciliate, the stigmas being slightly incurved.Bean (1988), Krüssman (1983) Sheet labelled U. davidiana Planch. var. japonica (Rehd.), Hokkaido specimen (new leaves and samarae), 1978 Trees grown from seed at Great Fontley in southern England first flowered aged 13 years.Brookes, A. H. (2025). Great Fontley Elm Trial, 2025 Report. Butterfly Conservation, Lulworth, England. The species does not sucker from roots.

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. 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 but is moderately susceptible to elm yellows.

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,Elwes, H. J. & Henry, A. (1913). The Trees of Great Britain & Ireland. Vol. VII., p.1924 Republished 2004 Cambridge University Press whence two seedlings were donated to Kew Gardens, London, in 1897. The Späth nursery, Berlin, marketed Japanese elm in Europe from 1900,Späth Catalogue No.106, p.124 (1900-1901) Kew obtaining a third specimen from them in that year.Elwes and Henry (1913), p.1924 Specimens were supplied by Späth to the Royal Botanic Garden Edinburgh in 1903 as U. campestris japonica Sheet described as U. campestris japonica, RBGE specimen from Späth nursery, 1903 and may survive in Edinburgh, as it was the practice of the Garden to distribute trees about the city.RBGE Cultivated Herbarium Accessions Book: Oct. 1958 notes by Ronald Melville on specimen C2698 A specimen of U. campestris japonica obtained from Späth stood in the Ryston Hall arboretum, Norfolk, in the early 20th century. The Arnold Arboretum specimens grew rapidly, and first flowered aged 12 years. A form from western China, for many years distinguished as U. wilsoniana Schneider, was introduced to the Arnold Arboretum in 1910. The Morton Arboretum, Illinois, has intermediate forms labelled U. japonica × U. wilsoniana. U. japonica × U. wilsoniana, Morton Arboretum, cirrusimage.comU. japonica × U. wilsoniana, Morton Arboretum, acc. no. 495-64, vplants.org 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. 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.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. . Photograph of Japanese elm in the Netherlands

The tree was briefly propagated and marketed in the UK by the Hillier & Sons nursery, Winchester, Hampshire from 1971 to 1977.Hillier & Sons (1977). Catalogue of Trees & Shrubs. Hillier, Ampfield, UK.Hillier & Sons Sales inventory 1962 to 1977 (unpublished). 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.

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

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'.Johnson, O. (2011). Champion Trees of Britain & Ireland,  p.168. Kew Publishing, Kew, London. . The oldest putative specimen in Edinburgh, possibly one of those supplied as U. campestris japonica by Späth in 1903, had a bole-girth of about 3.5 m (felled 2018).Tree labelled Japanese elm by 'Friends of the Meadows and Bruntsfield Links', in Coronation Walk, The Meadows, Edinburgh: fombl.org.uk Putative Japanese elm, Coronation Walk, The Meadows, Edinburgh, 1989Bark of putative Japanese elm, Coronation Walk, The Meadows, Edinburgh, 1989

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; five were also raised in the United States . Burgundy Glow = Discovery JFS-Bieberich = (formerly treated under U. propinqua Koidz.) JFS-KW2UD = Jacan Jeffree = Mitsui Centennial Prospector (formerly treated under Wilson's elm U. wilsoniana C.K. Schneid.) Reseda Thomson Validation. 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. The London office of Mitsui & Co. imported and distributed a number of the Canadian cultivars ('Thomson', 'Jacan' and 'Mitsui Centennial'), to commemorate its centenary in 1980; the majority went to Brighton & Hove City Council, while several were obtained by the Sir Harold Hillier Gardens, whence one was removed and planted outside the Elm Tree Inn at Swanwick to commemorate the centenary of Hampshire County Council in 1989. The USDA cultivar 'Prospector' was imported into the UK in 2009 by the Hampshire & Isle of Wight Branch, Butterfly Conservation.

Hybrids and hybrid cultivars Ulmus × mesocarpa, a natural hybrid of U. davidiana var. japonica and Ulmus macrocarpa was discovered in South Korea in the 1980s.Kim, M., & Lee, S. (1989). Korean J. Pl. Taxon. 19(1) (1989)

The hybrid Ulmus davidiana var. japonica × U. minor was raised at the Arnold Arboretum before 1924.The Morton Arboretum Living Collection, Ulmus list, quercus.mortonarb.org

The Japanese elm was widely used in the US in hybridization experiments at the Morton Arboretum and University of Wisconsin,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, USSmalley, 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 resulting in the release of the following cultivars: Cathedral Morton =