Ulmus procera

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Ulmus procera
PP-5-71990 (25).JPG
English Elm, Preston Park, Brighton, UK. Peter Bourne, 2009.
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Rosids
Order: Rosales
Family: Ulmaceae
Genus: Ulmus
Species: U. procera
Binomial name
Ulmus procera
Salisb.
Synonyms
  • Ulmus atinia Walker
  • Ulmus campestris L., Loudon, Planch., Moss
  • Ulmus minor var. vulgaris Richens
  • Ulmus sativa Mill.
  • Ulmus suberosa Smith, Loudon, Lindley
  • Ulmus surculosa Stokes var. latifolia Stokes, Ley

Ulmus procera Salisb., the English, Common, or more lately Atinian, Elm was, before the advent of Dutch elm disease, the commonest field elm in southern England, though not native there, and one of the largest and fastest-growing deciduous trees in Europe. R. H. Richens had noted that there are elm-populations in north-west Spain, in northern Portugal and on the Mediterranean coast of France that "closely resemble the English Elm" and appear to be "trees of long standing" in those regions rather than recent introductions.[1] Augustine Henry had earlier noted that the English Elms planted extensively in the Royal Park at Aranjuez from the late 16th century onwards, specimens said to have been introduced from England by Philip II[2] and "differing in no respects from the English Elm in England", behaved as native trees in Spain and "produced every year fertile seed in great abundance". He suggested that the tree "may be a true native of Spain, indigenous in the alluvial plains of the great rivers, now almost completely deforested".[3]

Richens believed that English Elm was a particular clone of the variable species Ulmus minor, referring to it as Ulmus minor var. vulgaris.[4] A 2004 survey of genetic diversity in Spain, Italy and the UK confirmed that English Elms are indeed genetically identical, clones of a single tree, the Atinian Elm once widely used for training vines, and brought to the British Isles by Romans for the purpose of supporting and training vines.[5] Thus, despite its name, the origin of the tree is widely believed to be Italy, although it is possible it hailed from what is now Turkey, where it is still used in the cultivation of raisins.[6][7]

Dr Max Coleman of the Royal Botanic Garden, Edinburgh writes (2009): "The advent of DNA fingerprinting has shed considerable light on the question. A number of studies have now shown that the distinctive forms that Melville elevated to species and Richens lumped together as field elm are single clones, all genetically identical, that have been propagated by vegetative means such as cuttings or root suckers. This means that enigmatic British elms such as ... English Elm have turned out to be single clones of field elm."[8] Since clones cannot pollinate identical clones, it follows that the fertile seed that Henry gathered from the English Elms at Aranjuez must have resulted from natural hybridisation with local elms, probably U. minor. At higher altitudes in Spain, he added, such as in Madrid and Toledo, the introduced English Elm did not set fertile seed.

Most current taxonomies, however, do not list English Elm under the heading "Ulmus minor var.".

Description[edit]

The tree often exceeded 40 m in height with a trunk < 2 m d.b.h.[9] The largest specimen ever recorded in England, at Forthampton Court, near Tewkesbury, was 46 m tall.[10] While the upper branches form a fan-shaped crown, heavy more horizontal boughs low on the bole often give the tree a distinctive 'figure-of-eight' silhouette. The small, reddish-purple hermaphrodite apetalous flowers appear in early spring before the leaves. The leaves are dark green, almost orbicular, < 10 cm long, without the pronounced acuminate tip at the apex typical of the genus. They flush a lighter green in April, about a month earlier than most Field Elm. Since the tree does not produce long shoots in the canopy, it does not develop the markedly pendulous habit of some Field Elm. The bark of old trees is scaly, unlike the vertically-furrowed bark of ancient Field Elm. The bark of English Elm suckers, like that of Dutch Elm suckers and some Field Elm, can be corky, but Dutch Elm suckers may be distinguished from English by their straighter, stouter twigs, bolder 'herringbone' pattern, and later flushing.

The tree does not produce fertile seed as it is female-sterile, and natural regeneration is entirely by root suckers.[4][11][12] Seed production in England was often unknown in any case.[13] By the late 19th century, urban specimens in Britain were often rooted-grafted on to wych elm root-stock to eliminate suckering; Henry noted that this method of propagation seldom produced good specimens.[14]

Pests and diseases[edit]

Owing to its homogeneity, the tree has proven particularly susceptible to Dutch elm disease, but immature trees remain a common feature in the English countryside courtesy of the ability to sucker from roots. After about 20 years, these suckers 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.[15] It was an ideal subject for such an experiment, as its sterility meant there was no danger of its introgression into the countryside.

In the USA, U. procera was found to be one of the most preferred elms for feeding by the Japanese Beetle Popillia japonica.[16]

The leaves of the English Elm in the UK are mined by Stigmella ulmivora.

Uses[edit]

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. It is also very resilient to crushing damage and these two properties led to its widespread use in the construction of jetties, timber piers and lock gates etc. It was used to a degree in furniture manufacture but not to the same extent as oak, because of its greater tendency to shrink, swell and split, which also rendered it unsuitable as the major timber component in shipbuilding and building construction. The wood has a density of around 560 kg per cubic metre.[17]

However, English Elm is chiefly remembered today for its aesthetic contribution to the English countryside, where it sometimes occurred in densities of over 1000 per square kilometre. In 1913 Henry Elwes wrote that "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".[10]

Cultivation[edit]

'The Vintage in Tuscany', 1849.
The Cam near Trinity College, Cambridge [Unknown artist]: a grove of mainly English Elm on the Backs [18]

Although there is no record of its introduction to Britain, the tree probably arrived with the Romans, a hypothesis supported by the discovery of pollen in an excavated Roman vineyard. It is possible the tree was used also as a source of leaf hay. The introduction of the tree to Spain from Italy is recorded by the Roman agronomist Columella.[19] English Elm, said to have been brought to Spain from England by Philip II, was planted extensively in the Royal Park at Aranjuez and the Retiro Park, Madrid from the late 16th century onwards.[20][21] It has also been identified as the elm grown in the vineyards of the Valais, or Wallis, canton of Switzerland.

More than a thousand years after the departure of the Romans from Britain, English Elm found far greater popularity, as the preferred tree for planting in the new Hawthorn hedgerows appearing as a consequence of the Enclosure movement, which lasted from 1550 to 1850. In parts of the Severn Valley, the tree occurred at densities of over 1000 per square kilometre, so prolific as to have been known as the 'Worcester Weed'.[22] In the eastern counties of England, however, hedgerows were usually planted with local Field Elm, or with suckering hybrids.[23] When elm became the tree of fashion in the 18th and 19th centuries, avenues and groves of English Elm were often planted, among them the Grand Avenue at Stowe House and the elm-groves in The Backs, Cambridge.

Notable trees[edit]

Mature English Elms are now only very rarely found beyond Brighton in the UK (see below), although some still survive on the Isle of Man. One large tree still survives in Leicester in Cossington Street Recreation Ground. Several survive (2013) in Edinburgh: one in Rosebank Cemetery (bole-girth 3 metres), two in Founders Avenue, Fettes College (bole-girth 2.5 metres), and one each in Inverleith Park (east avenue) and on Easter Warriston Green. A majestic open-grown specimen (bole-girth 3 metres) in Claremont Park, Leith Links, Edinburgh, retains the dense fan-vaulted crown iconic in the species. There is an isolated mature English Elm in the cemetery at Dervaig, Isle of Mull, Scotland.

As a consequence of Empire, some of the most significant remaining stands are to be found overseas, notably in Australia where they line the streets of Melbourne, protected by geography and quarantine from disease.[24] However, many of these trees, now over 100 years old, are succumbing to old age, and are being replaced with new trees raised by material from the older trees budded onto Wych Elm Ulmus glabra rootstock.[25] The tree has been widely planted in New Zealand, and is still commonly found in Auckland where it is regarded at its best as a street tree.[26] In the USA, several fine trees survive in New York City, notably the Hangman's Elm in Washington Square Park; [27] it was also planted as a street tree on the West Coast, notably in St Helena, California [28]

Brighton and the 'cordon sanitaire'[edit]

Sign on A27 road, Brighton, UK

Although the English Elm population in Britain was almost entirely destroyed by Dutch elm disease, mature trees can still be found along the south coast Dutch Elm Disease Management Area in East Sussex. This 'cordon sanitaire', aided by the prevailing south westerly onshore winds and the topographical niche formed by the South Downs, has saved many mature elms. Amongst these are possibly the world's oldest surviving English Elms, known as the 'Preston Twins' in Preston Park, both with trunks exceeding 600 cm in circumference (2.0 m d.b.h.).

Cultivars[edit]

There has been a small number of putative cultivars raised since the early 19th century,[30] three of which have now almost certainly been lost to cultivation:

Though usually listed as one of its cultivars, Ulmus Louis van Houtte "cannot with any certainty be referred to as Ulmus procera" (W. J. Bean).[9]

Hybrids[edit]

The English Elms at Aranjuez hybridised naturally from the 16th century to the 19th with local Spanish elms, probably U. minor (see above), producing "fertile seed in great abundance",[31] seed which was said to have been taken "all over Europe", presumably in the hope that it would grow into trees like the royal elms of Spain.[32]

Hybrid cultivars[edit]

Crossability experiments conducted at the Arnold Arboretum in the 1970s apparently succeeded in hybridizing the species with U. glabra and U. rubra, both also protogynous species. However, the same experiments also shewed the species to be self-compatible which, in the light of its proven female-sterility, must cast doubt on the identity of the specimens used.[33]

Accessions[edit]

North America[edit]

Europe[edit]

Australasia[edit]

See also[edit]

The Elm and the Vine

References[edit]

  1. ^ Richens, R. H., Elm (Cambridge, 1983), p.18, p.90
  2. ^ Richens, R. H., Elm (Cambridge, 1983), p.276
  3. ^ Elwes, H. J., & Henry, A., The Trees of Great Britain & Ireland (Private publication, Edinburgh, 1913), Vol. VII, p.1908
  4. ^ a b Richens, R. H., Elm, Cambridge University Press, 1983 [1]
  5. ^ Tree News, Spring/Summer 2005,Publisher Felix Press
  6. ^ Gil, L., Fuentes-Utrilla, P., Soto, A., Cervera, M.T., Collada, C. (2004) English elm is a 2,000-year-old Roman clone; Nature, vol. 431, p. 1053. Nature Publishing Group, London.
  7. ^ "English elm 'brought by Romans'". BBC. 2004-10-28. Retrieved 2008-12-21. 
  8. ^ Max Coleman, ed.: Wych Elm (Royal Botanic Garden Edinburgh publication, 2009; ISBN 978-1-906129-21-7); p. 22
  9. ^ a b Bean, W. J. (1981). Trees and shrubs hardy in Great Britain. Murray, London.
  10. ^ a b Elwes, H. J. & Henry, A. (1913). The Trees of Great Britain & Ireland. Vol. VII. pp 1848-1929. Private publication. [2]
  11. ^ Stace, C. A. (1997). New Flora of the British Isles. Cambridge University Press.
  12. ^ White, J. & More, D. (2002). Trees of Britain & Northern Europe. Cassell's, London
  13. ^ Hanson, M. W. (1990). Essex Elm. Essex Naturalist, 10. Essex Field Club, 1990.
  14. ^ Elwes, H. J., & Henry, A., The Trees of Great Britain & Ireland (Private publication, Edinburgh, 1913), Vol. VII, p.1909
  15. ^ Meek, James (2001-08-28). "Scientists modify elm to resist disease that killed millions of trees in Britain". The Guardian (London). Retrieved 2010-05-26. 
  16. ^ Miller, F., Ware, G. and Jackson, J. (2001). Preference of Temperate Chinese Elms (Ulmuss spp.) for the Feeding of the Japanese Beetle (Coleoptera: Scarabaeidae). Journal of Economic Entomology 94 (2). pp 445-448. 2001. Entom. Soc.of America.
  17. ^ Elm. Niche Timbers. Accessed 19-08-2009.
  18. ^ Photographs of English Elms on the Backs in 101 Views of Cambridge, Rock Bros Ltd, c.1900
  19. ^ Columella, J. M. (c.A D 50) De re rustica
  20. ^ Elwes, H. J., & Henry, A., The Trees of Great Britain & Ireland (Private publication, Edinburgh, 1913), Vol. VII, p.1908
  21. ^ Richens, R. H., Elm (Cambridge, 1983), p.276
  22. ^ Wilkinson, G. (1984). Trees in the Wild and Other Trees and Shrubs. Stephen Hope Books. ISBN 0-903792-05-2.
  23. ^ Richens, R. H., Elm (Cambridge, 1983), Ch.14
  24. ^ Spencer, R., Hawker, J. and Lumley, P. (1991). Elms in Australia. Australia: Royal Botanic Gardens, Melbourne. ISBN 0-7241-9962-4
  25. ^ Fitzgibbon, J. (2006) Royal Parade Elm Replacement. Elmwatch, Vol. 16 No. 1, March 2006
  26. ^ Auckland Botanical Society (2003). Journal Vol. 58 (1), June 2003. ISSN 0113-41332
  27. ^ Barnard, E. S. (2002). New York City Trees. Columbia University Press
  28. ^ Dreistadt, S, Dahlsten, D. L., and Frankie, G. W. (1990). Urban Forests and Insect Ecology. BioScience. Vol. 40, No. 3 (March 1990). pp. 192 - 198. University of California Press.
  29. ^ Clouston, B., Stansfield, K., eds., After the Elm (London, 1979), p.55
  30. ^ Green, P. S. (1964). Registration of cultivar names in Ulmus. Arnoldia, Vol. 24. Arnold Arboretum, Harvard University. [3]
  31. ^ Elwes, H. J., & Henry, A., The Trees of Great Britain & Ireland (Private publication, Edinburgh, 1913), Vol. VII, p.1908
  32. ^ Wilkinson, Gerald, Epitaph for the Elm (London, 1978), p.115
  33. ^ Hans, A. S. (1981). Compatibility and Crossability Studies in Ulmus. Silvae Genetica 30, 4 - 5 (1981).
  34. ^ "National Elm Collection annual report - Brighton & Hove City Council". Brighton-hove.gov.uk. Retrieved 2012-11-02. 
  35. ^ Johnson, Owen (ed.) (2003). Champion Trees of Britain & Ireland. Whittet Press, ISBN 978-1-873580-61-5.
  36. ^ http://www.forestry.gov.uk/forestry/infd-62qk8w
  37. ^ [4][dead link]
  38. ^ "Waite Arboretum | Waite Arboretum". Waite.adelaide.edu.au. 2003-01-21. Retrieved 2012-11-02. 

External links[edit]