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The Wych Elm Ulmus glabra Huds., or Scots Elm', is a large deciduous tree native to Europe, Asia Minormarker, and the Caucasus. Essentially a montane species, the tree occurs as far north as latitude 67°N at Beiarnmarker in Norway and has also been successfully introduced to Narsarsuaqmarker, near the southern tip of Greenlandmarker (61°N). The tree was by far the most common elm in the north and west of the British Islesmarker, , and is now acknowledged as the only truly native species. Closely related species such as Bergmann's Elm U. bergmanniana and Manchurian Elm U. laciniata, native to north-east Asia, were once sometimes included in Ulmus glabra . Another close relative is the Himalayan Elm U. wallichiana.

Description

The Wych Elm sometimes reaches heights of 40 m, typically with a broad crown supported by a short bole 2 m. d.b.h, and is notable for its very tough, supple young shoots. The leaves are deciduous, alternate, simple ovate or obovate with a lop-sided base, 6-17 cm long and 3-12 cm broad; the upper surface is rough. Leaves on vigorous shoots are sometimes three-lobed near the apex. The hermaphrodite flowers appear before the leaves in early spring, produced in clusters of 10-20; they are 4 mm across on 10 mm long stems and, being wind-pollinated, are apetalous. The fruit is a winged samara 20 mm long and 15 mm broad, with a single round 6 mm seed in the centre, maturing in late spring .

Pests and diseases

While the species is highly susceptible to Dutch elm disease. , it is less favoured as a host by the elm bark beetles which act as vectors. Research in Spain has indicated that it is the presence of a triterpene, alnulin, which renders the tree bark less attractive to the beetle than the Field Elm Ulmus minor 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). [51730] . The tree usually succumbs to disease a few years after achieving sexual maturity. In 1998, over 700 healthy, mature trees were discovered on the upper slopes of Mount Šimonka in Slovakiamarker, but it is now believed they had survived courtesy of their isolation from disease-carrying beetles rather than any innate resistance; 50 clones of these trees were presented to HRH The Prince of Wales for planting at his Highgrovemarker estate, and at Claphammarker, Yorkshiremarker [51731]. Indeed, DNA analysis by Cemagref in France has determined that genetic diversity within the species is very limited, making the chances of a resistant tree evolving rather remote. Nevertheless, the spread of Dutch elm disease to Scotland has revealed a number of Wych elm apparently surviving there unscathed, prompting the Royal Botanic Garden Edinburghmarker to clone the trees and inoculate them with the fungus to determine any innate resistance.

In trials conducted in Italy, the tree was found to have a slight to moderate susceptibility to Elm Yellows, and a high susceptibility to the elm leaf beetle Xanthogaleruca luteola [51732] .

Cultivation

The tree is moderately light-demanding, requires deep, rich soils, and is intolerant of flooding and prolonged drought . Although rarely used as a street tree owing to its shape, it can be surprisingly tolerant of urban air-pollution, constricted growing conditions and severe pollarding, as evidenced by the survival of those in Tsimiski Avenue in central Thessalonikimarker, Greece.

As Wych Elm does not sucker from the roots, and any seedlings often consumed by uncontrolled deer populations, regeneration is very restricted, limited to sprouts from the stumps of young trees. The resultant decline has been extreme and the Wych Elm is now uncommon over much of its former range. Wych Elm is best propagated from seed, although softwood cuttings taken in early June will root fairly reliably. Propagation from hardwood cuttings is notoriously difficult, even under mist conditions.

Notable trees

The largest tree listed in the Tree Register of the British Isles [51733] (TROBI) is at Brahan in the Scottish Highlands; it has a girth of 703 cm (2.23 m d.b.h.) and a height of 24 m [51734]. Outside the Brighton area, among the rare survivors in the south of England [2009] is a mature specimen at the University College sports ground, Abingdon Road, Oxfordmarker. Notable specimens in Edinburghmarker are also to be found [2009] in Moray Place, Learmonth Gardens, Queen Street Gardens and The Meadows area.

Subspecies

Some botanists, notably Lindquist[51735] (1931) have proposed dividing the species into two subspecies:
  • Ulmus glabra subsp. glabra. In the south of the species' range. Leaves broad; trees often with a short, forked trunk and a low, broad crown.
  • Ulmus glabra subsp. montana (Stokes) Lindqvist. In the north of the species' range (northern Britain, Scandinavia). Leaves narrower; trees commonly with a long single trunk and a tall, narrow crown.
However, there is much overlap between populations in these characters and the distinction may be owing to environmental influence, rather than genetic variation; the subspecies are not accepted by Flora Europaea .

Cultivars

Camperdown Elm
Circa 43 cultivars have been raised although many, at least 30, are now probably lost to cultivation as a consequence of Dutch elm disease and/or other factors:

Hybrids

Hybrid cultivars

The tree has featured strongly in artificial hybridization experiments in Europe, notably at Wageningenmarker in the Netherlandsmarker, and a number of hybrid cultivars have been commercially released since 1960Green, P. S. (1964). Registration of cultivar names in Ulmus. Arnoldia. Vol. 24. Arnold Arboretum, Harvard University. [51736]. The earlier trees were raised in response to the initial Dutch elm disease pandemic that afflicted Europe after the First World War, and were to prove vulnerable to the much more virulent strain of the disease that arrived in the late 1960s. However, further research eventually produced several trees immune to disease that were released after 1989

Etymology

The word wych has its origins in Middle English wiche, from the Old English wice, meaning pliant or supple, and which also gives us wicker and weak. Owing to its former abundance in Scotland, it was occasionally known as the 'Scotch (sic) Elm'; the name Loch Lomondmarker is a corruption of the Gaelic Lac Leaman, or 'Lake of the Elms'.

Accessions

North America
Europe
Too numerous to list.
Australasia

Nurseries

North America
Only as cultivar 'Camperdownii'
Europe
Widely available. In the UK, nurseries stocking this tree can be found by using the plantfinder function of the Royal Horticultural Society's website. [51740] This tree is also stocked by many local nurseries and by the British Trust for Conservation Volunteers. [51741]
Australasia

Seed suppliers

References

  1. Richens, R. J. (1984) Elm, Cambridge University Press.
  2. Elwes, H. J. & Henry, A. (1913). The Trees of Great Britain & Ireland. Vol. VII. pp 1848–1929. Private publication, Edinburgh. [1]
  3. Bean, W. J. (1981). Trees and shrubs hardy in Great Britain, 7th edition. Murray, London.
  4. White, J. & More, D. (2003). Trees of Britain and Northern Europe. Cassell's, London
  5. Forestry Commission. Dutch elm disease in Britain, UK. [2]
  6. Brasier, C. M. (1996). New horizons in Dutch elm disease control. Pages 20–28 in: Report on Forest Research, 1996. Forestry Commission. HMSO, London, UK.[3]
  7. Mittempergher, L. & Santini, A. (2004). The History of Elm Breeding. Invest. Agrar.: Sist Recur For. 2004 13 (1), 161-177.
  8. CAB International (2005) Forestry Compendium. CAB International, Wallingford, UK
  9. Lindquist, B. (1931). Two varieties of North West European Ulmus glabra. Bot. Exch. Club Rep.
  10. Flora Europaea: Ulmus glabra
  11. Heybroek, H. (1983). The Dutch elm breeding program. In Sticklen & Sherald (Eds). Dutch elm disease research (Ch. 3). Springer Verlag, New York.

External links

  • http://northernontarioflora.ca/chklst.cfm?speciesid=1005114 Synonymy list.
  • http://en.sl.life.ku.dk/Faciliteter/GroenlandsArboretet/Skovplantninger.aspx The Forest Plantations (Greenland)



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