|Ulmus laevis subsp. var.||Russian Elm|
Ulmus laevis Pall., the European White Elm, yclept Fluttering Elm, Spreading Elm and, in the USA, 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 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 .
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.
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. In England, trees grown from seed flower in March, commencing at ages of between 7 and 12 years.
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.
|Standard Cyclopedia of Horticulture|
Ulmus laevis, Pall. (U. pedunculata, Foug. U. effusa, Willd. U. ciliata, Ehrh. U. racemosa, Borkh., not Thomas). Tree, attaining 100 ft., with spreading branches, forming a broad open head: branchlets pubescent, usually until the second year: buds glabrous, acute: lvs. oval or obovate, very unequal at base, acuminate, sharply doubly serrate, usually glabrous above, pubescent beneath, 2-4 in. long: fls. slender-pedicelled; calyx with 6-8 exserted stamens: fr. ovate, notched, the incision not reaching the nutlet. Cent. Eu. to W. Asia.— Rarely cult., and with less valuable wood. The trunk and the limbs are, as in the American elm, often clothed with short branchlets. CH
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.
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.
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.
- ↑ 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.
- ↑ 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. pp 1848-1929. Private publication. 
- ↑ White, J. & More D. (2003). The Trees of Britain & Northern Europe, Cassell's, London.
- ↑ Mittempergher, L. & Santini, A. (2004). The History of Elm Breeding. Invest. Agrar.: Sist Recur For. 2004 13 (1), 161-177.