Ulmus laevis

Ulmus laevis
European White Elm in winter

Llandegfan, Anglesey

Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Rosids
Order: Rosales
Family: Ulmaceae
Genus: Ulmus
Species: U. laevis
Binomial name
Ulmus laevis
Pall.
Synonyms
  • Ulmus acuta Dumrt.
  • Ulmus ciliata Ehrh.
  • Ulmus effusa Willd., Loudon, Willkomm, Fliche
  • Ulmus laevis var. celtidea Rogowicz
  • Ulmus laevis var. simplicidens (E. Wolf) Grudz.
  • Ulmus octandra Schkuhr
  • Ulmus pedunculata Foug.
  • Ulmus petropolitana Gand.
  • Ulmus racemosa (not Thomas), Borkh.
  • Ulmus reticulata Dumrt.
  • Ulmus simplicidens E. Wolf

Ulmus laevis Pall., called the European White-elm,[1] Fluttering Elm, Spreading Elm, Stately Elm and Russian Elm, is a large deciduous tree native to Europe, from France[2] northeast to southern Finland, east as far as the Urals, and southeast to Bulgaria and the Crimea; there is also a disjunct population in the Caucasus. Moreover, a small number of trees found in Spain is now considered a relict population rather than an introduction by man, and possibly the origin of the European population.[3]

Endemic to alluvial forest, U. laevis is rarely encountered at elevations above 400 m.[4] 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, its introduction has not been recorded, but it was known to be in commerce at Exeter by 1836.

Description

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,[5] 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.[6][7] Although the species is protandrous, levels of self-pollination are high[8] 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.).[9]

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.[10] Moreover, the tree is not favoured by the vector bark beetles, which colonize it only when there are no other elm alternatives available,[11] 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.[12] Research in Spain[13] 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.

The species has a slight to moderate susceptibility to Elm Yellows, but a very low susceptibility to the elm leaf beetle Xanthogaleruca luteola.[14]

Cultivation

U. laevis is essentially a riparian tree, able to withstand over 100 days of continual flooding.[15] Spanish trees were found to be calcifuge, preferring slightly acid, siliceous soils, and also drought-intolerant, their xylem vessels prone to drought-stress cavitation.[16] 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.[17]

The species was never widely introduced to the USA, 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.[18]

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.[17]

Notable trees

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).[19] Other veterans survive at Casteau, Belgium (bole-girth 5.15 m), in Rahnsdorf near Berlin (bole-girth 4.5 m)[20] and in Ritvala, Finland (bole-girth 4.49 m).[21] A lane of Ulmus laevis is found at Eibergen, Netherlands.

Ulmus laevis is occasionally planted as an ornamental tree in the UK. 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 today amid diseased native elm near Torpoint.[22] 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.

In the USA, a tree of 31.4 m (103 ft) in height grows at 3331 NE Hancock Street in Portland, Oregon; its age is not known.[23]

Uses

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.[24]

Propagation

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.[25]

Forms

In Russia several ornamental forms are recognized: f. aureovariegata, f. argentovariegata, f. rubra, and f. tiliifolia.

Cultivars

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 [26] A line of similar monopodial trees can be found (2015) on the island in the Truyère at Entraygues, France.

Hybrids

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.

Accessions

Europe

North America

Nurseries

References

  1. ↑ "BSBI List 2007". Botanical Society of Britain and Ireland. Archived from the original (xls) on 2015-02-25. Retrieved 2014-10-17.
  2. ↑ 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
  3. ↑ 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.
  4. ↑ Girard, S. (2007). Dossier: L'orme: nouveaux espoirs? Forêt entreprise No. 175, Juillet 2007, Institut pour le developpement forestier, Paris.
  5. ↑ Harris, E. (1996). The European White Elm in Britain. Quarterly Journal of Forestry, Vol. 90, No. 2. 122-123. Royal Forestry Society.
  6. ↑ Bean, W. J. (1981). Trees and shrubs hardy in Great Britain, 7th edition. Murray, London.
  7. ↑ Elwes, H. J. & Henry, A. (1913). The Trees of Great Britain & Ireland. Vol. VII. 1848–1929. Republished 2004 Cambridge University Press, ISBN 9781108069380
  8. ↑ Hans, A. S. (1981). Compatibility and Crossability Studies in Ulmus. Silvae Genetica 30, 4 - 5 (1981).
  9. ↑ Brookes, A. H. (2015). Great Fontley Elm Trial, 2015 Report. Butterfly Conservation, Lulworth, UK.
  10. ↑ Solla et al. (2005). Screening European Elms for Resistance to Ophiostoma novo-ulmi. Forest Science, 134–141. 51 (2) 2005. Society of American Foresters.
  11. ↑ 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.
  12. ↑ 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), pp. 199-204. Royal Botanical Society of Belgium.
  13. ↑ 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).
  14. ↑ Mittempergher, L. & Santini, A. (2004). The History of Elm Breeding. Invest. Agrar.: Sist Recur For. 2004 13 (1), 161-177.
  15. ↑ Spohn, M. (2008). Trees of Britain & Europe (Black's Nature Guides), 256 p. A & C Black, ISBN 978-140810152-0
  16. ↑ 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.
  17. 1 2 Brookes, A. H. (2015). Disease-resistant elms, Butterfly Conservation trials report, 2015 Butterfly Conservation, Hants & IoW Branch, England.
  18. ↑ Spencer, R., Hawker, J. and Lumley, P. (1991). Elms in Australia, Royal Botanic Gardens, Melbourne, Australia. ISBN 0-7241-9962-4
  19. ↑ http://www.patriarchinatura.it
  20. ↑ http://www.bemerkenswerte-baeume.de, www.stadtentwicklung.berlin.de,
  21. ↑ http://www.monumentaltrees.com
  22. ↑ http://www.cornwall.gov.uk/default.aspx?page=13849
  23. ↑ "Ulmus laevis | Heritage Trees by Species | The City of Portland, Oregon". Retrieved 2015-08-27.
  24. ↑ 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
  25. ↑ 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.
  26. ↑ Bolle, C. (1888). Ulmus effusa, in Garden & Forest, 32, 381–382, 1888. Garden & Forest Publishing Co. Ltd., USA.
  27. ↑ http://lapetiteloiterie.free.fr/html/presentation/especes.html
  28. ↑ http://www.biologie.uni-ulm.de/extern/guenterstal/ukarbtxt.htm
  29. ↑ http://www.forestry.gov.uk/forestry/infd-62qk8w
  30. ↑ http://www.bbg.org/cgi/bgbase/search.cgi
  31. ↑ Ulmus laevis at Morton Arboretum
  32. ↑ http://www.arboretum-waasland.be/English.htm
  33. ↑ http://www.plantago.nl/plantindex/index.htm
  34. ↑ http://www.crown-nursery.co.uk
  35. ↑ http://www.dulford-nurseries.co.uk
  36. ↑ http://www.landcare.pwp.blueyonder.co.uk
  37. ↑ http://lve.ulmer.de/TUlEPTUwOTY4.html?UID=BEA9FD32B9D84066636F075F113998FB30EF481B64C697
  38. ↑ http://www.umbraflor.it

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