Ulmus procera
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| Ulmus procera | ||||||||||||||
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| Image:PP-5-71990 (25).JPG English Elm, Preston Park, Brighton.
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| Ulmus procera Salisb. | ||||||||||||||
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Ulmus procera Salisb., the English Elm or Atinian Elm was, before the advent of Dutch elm disease, one of the largest and fastest-growing deciduous trees in Europe, often exceeding 40 m in height with a trunk up to 2 m d.b.h diameter [1]. The largest specimen ever recorded in England, at Forthampton Court, near Tewkesbury, was 46 m tall [2]. The leaves are dark green, almost orbicular, < 10 cm long, without the pronounced acuminate tip at the apex typical of the genus. Wind-pollinated, the small, reddish-purple hermaphrodite flowers are without petals, and appear in early spring before the leaves . The tree does not produce fertile seed, and propagation is entirely by root suckers [3] [4] [5].
A survey of genetic diversity in Spain, Italy and the UK [6] [3] revealed that the English Elms are genetically identical, clones of a single tree, the Atinian Elm once widely used for training vines. Although there is no record of its introduction to Britain, it probably arrived with the Romans, a hypothesis supported by the discovery of pollen in an excavated Roman vineyard. The introduction of the tree to Spain from Italy is recorded by the Roman agronomist Columella in his treatise De Re Rustica, written circa AD 50; it has also identified it as the elm grown in the vineyards of the Valais, or Wallis, canton of Switzerland.
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[edit] Dutch elm disease
- For more detailed information on the disease, see Dutch elm disease
Owing to its homogeneity, the tree has proven particularly susceptible to Dutch elm disease, but immature trees remain a common feature in English hedgerows courtesy of the ability to sucker from roots. After about 20 years, these too become infected by the fungus and killed back to ground level. English Elm was the first elm to be genetically engineered to resist disease, at the University of Abertay Dundee [4]. It was an ideal subject for such an experiment, as its sterility meant there was no danger of its introgression into the countryside.
[edit] Brighton and the 'cordon sanitaire'
The English Elm population in Britain was decimated by Dutch Elm Disease. Despite this, mature trees can still be found in the south coast Dutch Elm Disease Control Area in Sussex. This designated control area extends from the river Adur in the west approximately 30 km eastwards to Pevensey Bay, and inland by up to 10 km. Empowered by the Dutch Elm Disease (Restriction on Movement of Elms) (Amendment) Order 1988 [5], local authorities may order the destruction of any infected trees or timber, although in practice they usually do it themselves, successfully reducing the numbers of elm bark beetle Scolytus spp, the vector of Elm Disease. This 'cordon sanitaire', aided the prevailing south westerly onshore winds and the topographical niche formed by the South Downs, has saved many mature elms. Amongst these are the world's largest surviving English Elms, known as the 'Preston Twins' in Preston Park, both exceeding 600 cm in circumference. Mature English Elms are now rarely found beyond Brighton's parks in England, however many still survive in Edinburgh, Scotland; especially around the Meadows and Bruntsfield Links, as yet undiscovered by the beetles.
[edit] Overseas trees
As a consequence of Empire, some of the most significant remaining stands are to be found overseas, notably in Australia [7] where they line the streets of Melbourne, protected by geography and quarantine from disease. In the USA, several fine trees survive in New York, notably the Hangman's Elm in Washington Square Park [8].
[edit] Uses
The English Elm was once valued for many purposes, notably as water pipes from hollowed trunks, owing to its resistance to rot in saturated conditions. However, it is chiefly remembered today for its aesthetic contribution to the English countryside, where it sometimes occurred in densities of over 1000 per square kilometre. "Its true value as a landscape tree may be best estimated by looking down from an eminence in almost any part of the valley of the Thames, or of the Severn below Worcester, during the latter half of November, when the bright golden colour of the lines of elms in the hedgerows is one of the most striking scenes that England can produce" [2].
[edit] Cultivars
There have been as small number of cultivars raised since the early 19th century [9], three of which have now almost certainly been lost to cultivation:
[edit] Arboreta etc. accessions
[edit] North America
- Longwood Gardens, acc. no. L-2507.
- Morton Arboretum, acc. nos. 211-40, 756-60, 351-70.
[edit] Europe
- Brighton & Hove City Council, NCCPG Elm Collection.
- Grange Farm, Sutton St. James, Spalding, Lincolnshire, UK, acc. no. 518.
- Royal Botanic Garden Edinburgh, acc. no. not given.
- University of Copenhagen, Botanic Garden, one specimen, no details available.
- Westonbirt Arboretum [6],Tetbury, Glos., UK, four trees, listed as U. minor var. vulgaris (no planting dates nor acc. nos. available).
[edit] Australasia
- Eastwoodhill Arboretum [7], Gisborne, New Zealand, 12 trees, details not known.
- Waite Arboretum [8], University of Adelaide, Adelaide, Australia
[edit] Nurseries
[edit] North America
- Wild Thyme Farm [9]
[edit] Europe
[edit] Australasia
- Established Tree Planters Pty. Ltd., Wandin, Victoria, Australia. [11]
- Fleming's Nursery [12], Monbulk, Victoria, Australia
[edit] References
- ^ Bean, W. J. (1981). Trees and shrubs hardy in Great Britain. Murray, London.
- ^ a b Elwes, H. J. & Henry, A. (1913). The Trees of Great Britain & Ireland. Vol. VII. pp 1848-1929. Private publication. [1]
- ^ Richens, R. H. (1983). Elm. Cambridge University Press
- ^ Stace, C. A. (1997). New Flora of the British Isles. Cambridge University Press.
- ^ White, J. & More, D. (2002). Trees of Britain & Northern Europe. Cassell's, London
- ^ Cogulludo-Agustin, M. A., Agundez, D. & Gil, L. (2000) Identification of native and hybrid elms in Spain using isozyme gene markers; Heredity, August 2000, vol. 85. Nature Publishing Group, London.
- ^ Spencer, R., Hawker, J. and Lumley, P. (1991). Elms in Australia. Australia: Royal Botanic Gardens, Melbourne. ISBN 0724199624
- ^ Barnard, E. S. (2002). New York City Trees. Columbia University Press
- ^ Green, P. S. (1964). Registration of cultivar names in Ulmus. Arnoldia, Vol. 24. Arnold Arboretum, Harvard University. [2]
[edit] External links
- http://redwood.mortonarb.org/PageBuilder?cid=2&qid= Morton Arboretum Catalogue 2006de:Englische Ulme
nl:Engelse veldiep
