|European White Elm in winter|
Ulmus laevis Pall., called the European White-elm, Fluttering Elm, Spreading Elm, Stately Elm and Russian Elm, is a large deciduous tree native to Europe, from France northeast to southern Finland, east as far as the Urals, and southeast to Bulgaria and the Crimea; there are also disjunct populations in the Caucasus and Spain, the latter now considered a relict population rather than an introduction by man, and possibly the origin of the European population.
Endemic to alluvial forest, U. laevis is rarely encountered at elevations above 400 m. Most commonly found along rivers such as the Volga and Danube, it is one of very few elms tolerant of prolonged waterlogged, anoxic ground conditions. Although not possessed of an innate genetic resistance to Dutch elm disease, the species is rarely infected in western Europe. The White Elm is allogamous and is most closely related to the American Elm U. americana.
Not a native of the United Kingdom, the date of its introduction there has not been recorded. It was known to be in commerce at the Ford & Please nursery in Exeter by 1836, and is first mentioned by Loudon who noted a tree at White Knights, Reading, which in 1838 measured 19 m in height, suggesting it had been planted at the end of the 18th century.
Ulmus laevis is similar in stature to the Wych Elm, if rather less symmetric, with a looser branch structure and less neatly rounded crown. It typically reaches a height and breadth of > 30 m, with a trunk < 2 m d.b.h. The extensive shallow root system ultimately forms distinctive high buttresses around the base of the trunk. The leaves are deciduous, alternate, simple ovate with a markedly lop-sided base, < 10 cm long and < 7 cm broad, comparatively thin, often almost papery in texture and very translucent, smooth above with a downy underside. The leaves are shed earlier in autumn than other species of European elm. However, the tree is most reliably distinguished from other European elms by its long flower stems, averaging 20 mm. Moreover, the apetalous wind-pollinated flowers are distinctively cream-coloured, appearing before the leaves in early spring in clusters of 15-30; they are 3–4 mm across. The fruit is a winged samara < 15 mm long by 10 mm broad with a ciliate margin, the single round 5 mm seed maturing in late spring.
The species is most closely related to the American Elm U. americana, from which it differs mainly in the irregular crown shape and frequent small sprout stems on the trunk and branches, features which also give the tree a distinctive winter silhouette. Although the species is protandrous, levels of self-pollination can be high The tree can grow very rapidly; where planted in persistently moist soil, trunk width of 13-year-old trees increased by 4 cm per annum at breast height (d.b.h.).
Pests and diseases
Like other European elms, natural populations of the European White Elm have little innate resistance to Dutch elm disease, although research by Irstea has isolated clones able to survive inoculation with the causal fungus, initially losing < 70% of their foliage, but regenerating strongly the following year. Moreover, the tree is not favoured by the vector bark beetles, which colonize it only when there are no other elm alternatives available, an uncommon situation in western Europe. Indeed, in a study of elm in Flanders, not one example of U. laevis was found to be afflicted by Dutch elm disease. Research in Spain has indicated that it is the presence of a triterpene, alnulin, that renders the tree bark unattractive to the beetles. Ergo: the tree's decline in western Europe is chiefly owing to woodland clearance in river valleys, not disease. Moreover, it was noted by Jouin at Metz, and a century later by Mittempergher and Santini in Italy, that U. laevis had a very low susceptibility to the elm leaf beetle Xanthogaleruca luteola. However, Elwes noted that trees planted at Ugbrooke in Devon were infested with Cacopsylla ulmi, which he had never noted on any other elm in Britain.
U. laevis is essentially a riparian tree, able to withstand over 100 days of continual flooding. Spanish trees were found to be calcifuge, preferring slightly acid, siliceous soils, and also drought-intolerant, their xylem vessels prone to drought-stress cavitation. However, healthy trees approximately 100 years old were discovered in England planted around an ammunition dump on the elevated chalk of Salisbury Plain about 2 km from Stonehenge. The tree is comparatively weak-wooded, much more so than Field Elm Ulmus minor, and thus an inappropriate choice for exposed locations. In trials in southern England by Butterfly Conservation, young trees of <5 m height were badly damaged by gusts of 40 knots (75 km/h) in midsummer.
The species was never widely introduced to the United States, but is represented at several arboreta. In the Far East, the tree has been planted in Xinjiang province and elsewhere in Northern China; planting in Tongliao City is known to have been particularly successful. White Elm is also known to have been introduced to Australia.
In recent years, the tree has enjoyed a small renaissance in England. A popular larval host plant of the White-letter Hairstreak Satyrium w-album butterfly across Europe, the elm is now being planted by Butterfly Conservation and other groups to restore local populations decimated by the effects of Dutch elm disease on native or archaeophytic elms. The Cheshire Wildlife Trust, for example, has planted 1,000 White Elms on its reserves in the former Vale Royal district of the county.
The three largest known trees in Europe are at Gülitz in Germany (3.1 m d.b.h.), at Komorów in Poland (2.96 m d.b.h. in 2011), known as the Witcher (tree), and at Bergemolo in Piedmont, Italy (bole-girth 6.2 m, height 26 m., 2008). Other veterans survive at Casteau, Belgium (bole-girth 5.15 m), in Rahnsdorf near Berlin (bole-girth 4.5 m) and in Ritvala, Finland (bole-girth 4.49 m). A lane of Ulmus laevis is found at Eibergen, Netherlands.
Ulmus laevis has very occasionally been planted as an ornamental tree in the UK, and even more randomly in countryside hedgerows. The UK Champion is at Ferry Farm, Harewood, Cornwall (27 m high, 1.8 m d.b.h.). Other examples are few and far between but sometimes of great age, surviving amid diseased native elm near Torpoint, and near Over Wallop in Hampshire (16 m high, 1.3 m d.b.h.)  Others can be found in Edinburgh (East Fettes Avenue opposite Inverleith Allotments, North Merchiston Cemetery), London (Riverside Walk, near Royal Botanic Gardens, Kew, and at Peckham and Tooting), Brighton & Hove, and near St. Albans.
U. laevis near the Red House, Česká Lípa, Czech Republic
The timber of the White Elm is of poor quality, the cross-grain causing problems when machined, and thus of little practical use to man, not even as firewood. The density of the timber is significantly lower than that of other European elms. However, owing to its rapid growth, tolerance of soil compaction, air pollution and de-icing salts, the tree has long been used for amenity planting in towns and along roadsides.
Usually easy to grow from seed sown to a depth of 6 mm in ordinary compost and kept well-watered. However, as seed viability can vary greatly from year to year, softwood cuttings taken in June may be a more reliable method. The cuttings strike very quickly, well within a fortnight, rapidly producing a dense matrix of roots.
Subspecies and varieties
Several putative varieties have been identified. A variety celtidea from what is now the Ukraine was reported by Rogowicz in the middle of the 19th century, but no examples are known to survive. Another variety parvifolia has been reported from Serbia.
In Russia several ornamental forms are recognized: f. aureovariegata, f. argentovariegata, f. rubra, and f. tiliifolia.
Compared with the other European species of elm, U. laevis has received scant horticultural attention, there being only five recorded cultivars: Aureovariegata, Colorans, Ornata, Pendula, Punctata, Urticifolia.
A pyramidal form was reported in 1888 from the Fredericksfelde cemetery in Berlin by Bolle  A line of similar monopodial trees can be found (2015) on the island in the Truyère at Entraygues, France.
U. laevis does not hybridize naturally, in common with the American Elm U. americana to which it is closely related. However, in experiments at the Arnold Arboretum, it was successfully crossed with U. thomasii and U. pumila; no such crosses have ever been released to commerce.
- Arboretum de La Petite Loiterie, Monthodon, France. No details available
- Arboretum Freiburg-Günterstal, Germany, no details available
- Brighton & Hove City Council, UK, NCCPG Elm Collection. Ten trees at Hove Recreation Ground, Hove.
- Copenhagen University, Botanic Garden. No details available.
- ELTE Botanic Garden Budapest. Acc. nos. 1998-0718, 1998-0719.
- Grange Farm Arboretum, Sutton St. James, Spalding, Lincolnshire, UK. Acc. no. 502.
- Great Fontley Butterfly Conservation Elm Trials plantation, UK. Two planted 2003, grown from cuttings of specimen at RBG Wakehurst Place. Acc. no. 1973-21048.
- Hortus Botanicus Nationalis, Salaspils, Latvia. Acc. nos. 18136, 18140.
- Linnaean Gardens of Uppsala, Sweden. Acc. no. 1930-1014.
- Royal Botanic Garden Edinburgh, UK. Acc. no. 20070643, from seed wild collected in Val d'Allier, France.
- Royal Botanic Gardens Kew, UK. Acc. nos. 1969-17302, 1973-11712.
- Royal Botanic Gardens, Wakehurst Place, UK. Acc. no. 1973-21048.
- Tallinn Botanic Garden, Estonia. No accession details available.
- Thenford House arboretum, Oxfordshire, UK. No details available.
- 'The Leys', University Parks, Oxford, UK. Acc. no. 02678.
- Westonbirt Arboretum, Tetbury, Glos., UK, planted 1997. Acc. no. 1995/322
- Wijdemeren City Council, Netherlands, Elm Collection. Planted 1990 Tjalk, Loosdrecht; 2007 Hinderdam, Nederhorst den Berg; elm lane De Kwakel, Kortenhoef in 2009.
- Arnold Arboretum. Acc. nos. 17910, 637-79, 6951, 753-80.
- Brenton Arboretum, Dallas Center, Iowa. No details available.
- Brooklyn Botanic Garden, New York. Acc. no. X02589.
- Dominion Arboretum, Canada. No details available
- Longwood Gardens. Acc. nos. 1964-0568, 1964-1119.
- Morton Arboretum, Illinois. Acc. nos. 1302-27, 446-48, 492-64, 27-98.
- Arboretum Waasland, Nieuwkerken-Waas, Belgium.
- Boomkwekerij Oirschot, Oirschot, Netherlands
- Crown Nursery, Ufford, Suffolk, UK
- Dulford Nurseries, Cullompton, Devon, UK
- Landcare Tree Nursery, Old Sodbury, South Gloucestershire, UK
- Lorenz von Ehren, Hamburg, Germany
- Noordplant , Glimmen, Netherlands.
- UmbraFlor, Spello, Italy
- "BSBI List 2007". Botanical Society of Britain and Ireland. Archived from the original (xls) on 2015-02-25. Retrieved 2014-10-17.
- Photographs of U. laevis (L'Orme lisse) in France: in the Forêt du Romersberg, Moselle,  (bottom of page), and near Walbourg, Bas-Rhin, (top of page); Archive Krapo arboricole
- Fuentes-Utrilla, P., Squirrell, J., Hollingsworth, P. M. & Gil, L. (2006). Ulmus laevis (Pallas) in the Iberian Peninsula. An introduced or relict tree species? New data from cpDNA analysis. Genetics Society, Ecological Genetics Group conference, University of Wales Aberystwyth 2006.
- Girard, S. (2007). Dossier: L'orme: nouveaux espoirs? Forêt entreprise No. 175, Juillet 2007, Institut pour le developpement forestier, Paris.
- Harvey, J. (1974). Early Nurserymen. Phillimore & Co. Ltd. 1975. ISBN 978-0850331929
- Loudon, (1841). Gardener's Magazine, xviii, p.389, 1841.
- Harris, E. (1996). The European White Elm in Britain. Quarterly Journal of Forestry, Vol. 90, No. 2. 122–123. Royal Forestry Society.
- Bean, W. J. (1981). Trees and shrubs hardy in Great Britain, 7th edition. Murray, London.
- Elwes, H. J. & Henry, A. (1913). The Trees of Great Britain & Ireland. Vol. VII. 1848–1929. Republished 2004 Cambridge University Press, ISBN 9781108069380
- Hans, A. S. (1981). Compatibility and Crossability Studies in Ulmus. Silvae Genetica 30, 4 - 5 (1981).
- Brookes, A. H. (2015). Great Fontley Elm Trial, 2015 Report. Butterfly Conservation, Lulworth, UK.
- Solla et al. (2005). Screening European Elms for Resistance to Ophiostoma novo-ulmi. Forest Science, 134–141. 51 (2) 2005. Society of American Foresters.
- Collin, E., Bilger, I., Eriksson, G., & Turok, J. (2000). The conservation of elm genetic resources in Europe. In Dunn, C. P. (Ed.) (2000). The elms: breeding, conservation & disease management. Kluwer Academic Publishers, Boston.
- Vander Mijnsbrugge, K., Vanden Broeck, A., & Van Slycken, J. (2005). A study of Ulmus laevis in Flanders (Northern Belgium). Belgian Journal of Botany, Vol. 138, No. 2 (2005), 199–204. Royal Botanical Society of Belgium.
- Martín-Benito D., Concepción García-Vallejo M., Alberto Pajares J., López D. 2005. Triterpenes in elms in Spain. Can. J. For. Res. 35: 199–205 (2005). 
- Mittempergher, L. & Santini, A. (2004). The History of Elm Breeding. Invest. Agrar.: Sist Recur For. 2004 13 (1), 161–177.
- Jerinić-Prodanović, D. (2006). A new jumping louse, Cacopsylla ulmi Förster (Homoptera, Psyllidae) on elm in Serbia. Acta entomologica serbica. 2006, 11 (1/2): 11–18. 
- Spohn, M. (2008). Trees of Britain & Europe (Black's Nature Guides), 256 p. A & C Black, ISBN 978-140810152-0
- Venturas, M. et al. (2013). Ulmus laevis Pall. a native elm in the Iberian peninsula: a multidisciplinary approach. Abstracts. 3rd International Elm Conference 2013. The elm after 100 years of Dutch elm disease. Florence 2013. p.48.
- Brookes, A. H. (2015). Disease-resistant elms, Butterfly Conservation trials report, 2015 Butterfly Conservation, Hants & IoW Branch, England. 
- Spencer, R., Hawker, J. and Lumley, P. (1991). Elms in Australia, Royal Botanic Gardens, Melbourne, Australia. ISBN 0-7241-9962-4
- http://www.bemerkenswerte-baeume.de,  www.stadtentwicklung.berlin.de,
- BSBI, (2016). BSBI records for north Hampshire, vc. 12. Botanical Society of Britain & Ireland, Shirehampton, Bristol.
- Google Earth Street View, June 2015
- "Ulmus laevis | Heritage Trees by Species | The City of Portland, Oregon". Retrieved 2015-08-27.
- Collin, E. (2003). EUFORGEN Technical Guidelines for genetic conservation and use for European white elm (Ulmus laevis). IPGRI, Rome, Italy. ISBN 92-9043-603-4
- Jovanović, B. & Radulović, S. (1980). Ulmus laevis var. parvifolia. Glasn. Prir. Muz. u Beogradu. (Bulletin of the Natural History Museum, Belgrade). 35 : 32, 38 (1980). Belgrade, Serbia.
- Bolle, C. (1888). Ulmus effusa, in Garden & Forest, 32, 381–382, 1888. Garden & Forest Publishing Co. Ltd., USA.
- Ulmus laevis at Morton Arboretum
- Collin, E., 'Ulmus laevis: Technical Guidelines for Genetic Conservation and Use', euforgen.org (2003)
- Ecology of the European White Elm
- Ulmus laevis distribution map: linnaeus.nrm.se 
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