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

Description

The size and shape of the Japanese elm is extremely variable, 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, The Morton Arboretum, Illinois, distinguishes a cork-barked form from China, ''U. propinqua'' var. ''suberosa''. 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'. 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. Bean noted that the variety from western China, formerly known as ''U. wilsoniana'', has 16 to 22 pairs of leaf-veins, while the eastern type tree has not more than 16. 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, US

/ref> the seed touching the notch, the inner margins of which are ciliate, the stigmas being slightly incurved. Trees grown from seed at Great Fontley in southern England first flowered aged 13 years.Brookes, A. H. (2020). ''Great Fontley Elm Trial, 2020 Report''. Butterfly Conservation, Lulworth, England. The species does not sucker from roots.

File:Japanese elm.jpg, Japanese elm, showing pendulous habit of lower branchlets. SHHG, Romsey, UK
File:Japanese elm leaves.jpg, Japanese Elm leaves
File:David & Japanese elm leaves.jpg, David Elm (left) and Japanese Elm (right) leaves for comparison
File:Seed Ulmus davidiana var. japonica.jpg, Samarae
File:Bark of the Japanese Elm Ulmus davidiana var. japonica.jpg, Bark of 30-year-old tree

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 North America in 1890 as seed brought by William Smith Clark and planted at the University of Massachusetts. This was after years of his teaching from where later on Sapporo to the Arnold Arboretum, Massachusetts, whence two seedlings were donated to Kew Gardens, London, in 1897. The Späth nursery, Berlin, marketed Japanese elm in Europe from 1900, Kew obtaining a third specimen from them in that year. Specimens were supplied by Späth to the Royal Botanic Garden Edinburgh in 1903 as ''U. campestris japonica'' 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''. 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 Netherland

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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.

File:Memorial Tree of Pioneer of Shintotsukawa Town.jpg, Japanese elm, Kikusui Park, Shintotsukawa (2019)
File:Japanese Elm at Oyafuru.jpg, Japanese Elm at Oyafuru, Ishikari, Hokkaido (2020)
File: Hitomi Elm.jpg, Japanese elm, Sapporo (2010)
File:Hokkaido University - Library.jpg, Autumn colouring Hokkaido University Botanical Gardens, Sapporo
File:131103 Hokkaido University Sapporo Hokkaido Japan10s5.jpg, Japanese elms, Hokkaido University Botanical Gardens
File:131103 Hokkaido University Botanical Gardens Sapporo Hokkaido Japan04s3.jpg, Old tree in Hokkaido University Botanical Gardens, Sapporo
File:WP Japanese elm late leafing mid May GFF 2.jpg, Japanese elm in early May before leaf flushing, Great Fontley, UK

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).Bark of putative Japanese elm, Coronation Walk, The Meadows, Edinburgh, 1989
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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 State

'Discovery', 'JFS-Bieberich' = (formerly treated under ''U. propinqua'' Koidz.),
'Freedom', 'Jacan', '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.

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 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' = , 'Morton Glossy' = , 'Morton Plainsman' = , 'Morton Red Tip' = , 'Morton Stalwart' = , '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''.

Accessions

;North America
*Arnold Arboretum, US. Acc. nos. 4119 (from cult. material), 917-78, wild collected in Korea.
*Brenton Arboretum, US. Listed as ''U. wilsoniana''; no details available.
* Brooklyn Botanic Gardenbr>
New York City, New York, US. Acc. no. 780251 (listed as ''U. japonica'').
* Chicago Botanic Garden, US. 1 tree in the West Collections Area, listed as ''U. propinqua'' var. ''suberosa''.
*Dawes Arboretumbr>
US. 1 tree, no acc. details available.
* Holden Arboretum, US. Acc. nos. 80-664 (unrecorded provenance), 97-126, wild collected in Korea.
* Morton Arboretum, US. Acc. nos. 514-39, 679-62, 680-62, 354-U, 23-2008, 73-2011, also two others under the synonyms of ''U. propinqua'' Koidz. or cork bark elm (acc. no. 53-96), and ''U. propinqua'' Koidz. var. ''suberosa'', collected from the Nei Mongol Zizhiqu Autonomous Region, China
(acc. no. 52-95)

* U S National Arboretum, Washington, D.C., US. Acc. no. 68998. Also (listed under synonym ''U. japonica''): 76253, 76254, 76227, and (listed under syn. ''U. propinqua''): 76249, 68985, and (listed under ''U. propinqua'' var. ''suberosa''): 76234, 76244, 76241.

;Europe
*Brighton & Hove City Council, UK. NCCPG Elm Collection.
* Grange Farm Arboretum, Lincolnshire, UK. Listed as ''Ulmus japonica''; acc. no. 514
*Great Fontley, Fareham, UK, ''Butterfly Conservation'' Elm Trials plantation, planted 2002, grown from seed collected from the Great Elm, Hokkaido University, Sapporo, Japan.
*Hortus Botanicus Nationalis, Salaspils, Latvia. Acc. nos. 18128,29,30,31.
* Linnaean Gardens of Uppsala, Sweden, (as ''U. japonica''). Acc. no. 1998-1284, obtained from the Russian Federation, and 2001-1659, wild collected in South Kore

* Royal Botanic Garden Edinburgh, UK. Listed as ''U. japonica'', acc. no. 19031053.Royal Botanic Garden Edinburgh. (2017). ''List of Living Accessions: Ulmus'

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* Royal Botanic Gardens, Kew, Royal Botanic Gardens, Kew, UK. Acc. nos. 1995-581, 1995-1305
* Royal Horticultural Society Gardens, Wisley, UK. Listed as ''U. japonica'', no details available.
*Sir Harold Hillier Gardens, UK. Listed as ''U. japonica'', acc. nos. 1977.5234, 1977.5972, 1977.6373, 1982.4019.
* Tallinn Botanic Garden, Estonia

Listed as ''U. japonica'', no accession details available.
*Thenford House arboretum, Oxfordshire, UK, no details available.
*Wijdemeren City Council, Netherlands. Elm Arboretum, Brilhoek, Nederhorst den Berg, 2 planted in 2019 as U. propinqua.

Nurseries

;North America
*Patmore Nurser

Brandon, Manitoba, Brandon, Manitoba, Canada
*Sun Valley Garden Centr

Eden Prairie, Minnesota, US
;Europe
*Arboretum Waaslan

Nieuwkerken-Waas, Belgium

References

External links

USDA Plant Guide: ''Ulmus davidiana''efloras.org: ''U. davidiana'' var. ''japonica'' (illustrations 1 to 9)

* Sheet labelled ''U. davidiana'' Planch. var. ''japonica'' (Rehd.), Hokkaido specimen (new leaves and samarae), 1978
* Sheet described as ''U. campestris japonica'', RBGE specimen from Späth nursery, 1903
* From Chanyang, W. China (Wilson specimen, 1909)
* From Hupeh, C. China (Wilson specimen, 1907)
* From Szechuan, C. China (Schneider specimen, 1914)

{{Taxonbar, from=Q844010

davidiana var. japonica
Trees of China
Flora of China
Trees of Japan
Flora of Japan
Trees of Korea
Flora of Korea
Trees of Asia
Ulmus articles with images
Elm species and varieties