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Ulmus laevis Pall., the European White Elm, yclept Fluttering Elm, Spreading Elm and, in the USAmarker, Russian Elm, is a large deciduous tree native to Europe, from Francemarker northeast to southern Finlandmarker, east as far as the Uralsmarker, and southeast to Bulgariamarker and the Crimeamarker; there is also a disjunct population in the Caucasus. Moreover, a small number of trees found in Spainmarker is now considered a relict population rather than an introduction by man, and possibly the origin of the European population [141480] Fuentes-Utrilla, P., Squirrell, J., Hollingsworth, P. M. & Gil, L. (2006). Ulmus laevis (Pallas) in the Iberian Peninsulamarker. An introduced or relict tree species? New data from cpDNA analysis. Genetics Society, Ecological Genetics Group conference, University of Wales Aberystwyth 2006..

Essentially endemic to alluvial forest, it 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. The White Elm is allogamous and is most closely related to the American Elm U. americana.
Massive root structure exposed by bank erosion.
Photo: Eric Collin, CEMAGREF, France
Buttresses
Twig of young tree, with characteristic tubercules on bark.
Photo: Vincent Seigner, CEMAGREF, France
U. laevis flowers; note the long stems
U. laevis seed; note ciliate margins
U.laevis leaves and seeds
European White Elm, Alfriston, East Sussex, UK (2006)

Description

The tree 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 lop-sided base, 10 cm long and 7 cm broad, comparatively thin, often almost papery in texture and very translucent, with a downy underside. The apetalous wind-pollinated flowers appear before the leaves in early spring, produced in clusters of 15-30; they are 3-4 mm across on 20 mm long stems. 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. In England, trees grown from seed commenced flowering in their 12th year.

The tree is most reliably distinguished from other European elms by the long flower stems, and 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 .

U. laevis suckers from roots, but not stools. [141481]

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 Cemagref 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. Research in Spain 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). [141482] 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 [141483]. .

Cultivation

Although ideally suited to wet ground conditions, the tree can still grow, albeit more slowly, on drier sites including chalk downland. However, one overriding factor in choosing a site is Exposure. White Elm is comparatively weak-wooded, much more so than Field Elm Ulmus minor, and thus an inappropriate choice for windy 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 USAmarker, 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 Tongliaomarker 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, is planting 1,000 White Elms on its reserves [141484] in the former Vale Royalmarker district of the county.

Uses

The timber of the White Elm is of poor quality and thus of little use to man, not even as firewood. Its density is significantly lower than that of other European elms.

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.

Notable trees

The two largest known trees in Europe are at Gülitzmarker[141485] in Germanymarker (3.1 m d.b.h.), and Komorówmarker in Polandmarker (2.96 m d.b.h.). The UK Champion is at Ferry Farm, Harewood, Cornwallmarker (27 m high, 1.8 m d.b.h.). Other examples in the UKmarker are few and far between, but sometimes of great age. Several survive amid diseased native elm near Torpointmarker in Cornwallmarker [141486]; others can be found in Edinburghmarker (The Meadows area); Londonmarker (Riverside Walk, near Royal Botanic Gardens, Kew, and at Peckhammarker and Tootingmarker); Chelmsfordmarker (beside the Chelmermarker at the Rivermead Campus) [2009]; Brighton & Hovemarker; and near St. Albansmarker. In the USA, a reputedly magnificent tree grows in Portlandmarker, Oregonmarker, but its dimensions and age are not known.

Subspecies and varieties

The species is not divided into subspecies or varieties. A variety celtidea (occasionally treated as a species) from what is now the Ukrainemarker was reported by Rogowicz in the middle of the 19th century, but no examples are known to survive.

Forms

In Russiamarker several decorative forms are recognized: f. aureovariegata, f. argentovariegata, f. rubra, and f. tiliaefolia.

Cultivars

Compared with the other European species U. glabra and U. minor, U. laevis has received scant horticultural attention, there being only five recorded cultivars, none of which are known to remain in cultivation, with the possible exception of 'Colorans':Aureo-Variegata, Colorans, Ornata, Punctata, Urticaefolia.

Hybrid cultivars

U. laevis does not hybridize naturally, in common with the American Elm U. americana to which it is closely related. The few reported instances of artificial hybridization in the 19th century are now regarded with suspicion.

Accessions

North America
Europe

Nurseries

North America
None known
Europe

Seed suppliers

References

  1. Girard, S. (2007). Dossier: L'orme: nouveaux espoirs? Forêt entreprise No. 175, Juillet 2007, Institut pour le developpement forestier, Paris.
  2. Bean, W. J. (1981). Trees and shrubs hardy in Great Britain, 7th edition. Murray, London.
  3. Elwes, H. J. & Henry, A. (1913). The Trees of Great Britain & Ireland. Vol. VII. pp 1848-1929. Private publication. [1]
  4. White, J. & More D. (2003). The Trees of Britain & Northern Europe, Cassell's, London.
  5. 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.
  6. Mittempergher, L. & Santini, A. (2004). The History of Elm Breeding. Invest. Agrar.: Sist Recur For. 2004 13 (1), 161-177.
  7. Spencer, R., Hawker, J. and Lumley, P. (1991). Elms in Australia, Royal Botanic Gardens, Melbourne, Australia. ISBN 0724199624
  8. Brookes, A. H. (2006). An evaluation of disease-resistant hybrid and exotic elms as larval host plants for the White-letter Hairstreak Satyrium w-album, Part 1. [2]. Butterfly Conservation. Lulworth, UK.

External links

  • http://www.fao.org/docrep/006/AD110E/AD110E01.htm Flora of the Korqin Sandy Lands, China.
  • http://www.bioversityinternational.org/publications/Pdf/921.pdf Ecology of the European White Elm
  • http://www.wildlifetrust.org.uk/cheshire/news_white_letter_hairstreak.htm The Vale Royal White-letter Hairstreak Project, Cheshire Wildlife Trust, UK



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