European White Elm
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| iEuropean White Elm | ||||||||||||||
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 European White Elm in winter
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| Ulmus laevis Pall. |
The European White Elm Ulmus laevis is a large tree native to Europe, from France northeast to southern Finland, and southeast to Bulgaria and the Crimea; there is also a disjunct population in the Caucasus. Essentially a riparian species, it is most commonly encountered along rivers such as the Volga and Danube. It is the only elm tolerant of waterlogged ground, its massive shallow root system forming distinctive high buttresses around the base of the trunk.
Like other European elms, it has little innate resistance to Dutch elm disease, but is eschewed by the vector bark beetles and only rarely becomes infected. Its decline in Europe is chiefly owing to woodland clearance in river valleys. Introduced specimens in Britain are few and far between, but sometimes of great age. Several old trees survive amid diseased native elm near Torpoint in Cornwall [1].
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Similar in stature to the Wych Elm, it typically reaches a height of over 30m and a trunk diameter of up to 2 m. The leaves are deciduous, alternate, simple ovate with a lop-sided base, <10 cm long and <7 cm broad, rough above, and downy underneath. The flowers appear before the leaves in early spring, produced in clusters of 15-30 together; they are 3-4 mm across on 20 mm long stems, have no petals and are wind-pollinated. The fruit is a winged samara 15 mm long and 10 mm broad with a single round 5 mm seed maturing in late spring.
The tree is 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. Unlike the other European species, it does not hybridize naturally, and the few reported instances of artificial hybridization are now regarded with suspicion.
The species was never widely introduced to the USA, but is represented at the Longwood Gardens, Pennsylvania, and the Arnold Arboretum, Massachusetts. In Canada, a specimen is grown at the Dominion Arboretum. In the Far East, it has been planted in Xinjiang and elsewhere in Northern China; planting in Tongliao City is known to have been particularly successful. The tree is not known to have been introduced to Australasia.
[edit] References
- Bean, W. J. (1981). Trees and shrubs hardy in Great Britain, 7th edition. Murray, London.
- Brookes, A. H. (2006). An evaluation of disease-resistant hybrid and exotic elms as larval host plants for the White-letter Hairstreak butterfly Satyrium w-album, Part 1. Butterfly Conservation, Lulworth, UK.
- 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.
- Elwes, H. J. & Henry, A. (1913). The Trees of Great Britain & Ireland. Vol. VII. pp 1848-1929. Private publication. [2]
