Smooth-leaved Elm
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 Smooth-leaved Elm leaves
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| Ulmus minor subsp. minor Richens |
The Smooth-leaved Elm Ulmus minor subsp. minor Richens (syn. U. carpinifolia) or Narrow-leaved Elm is a subspecies of the Field Elm native to southern Europe and Asia Minor (including Iran). It is believed to have been introduced to northern Europe, including England, by Man during the Bronze Age. It is a deciduous tree once <35 m tall, the scientific synonym alluding to the superficial similarity of the leaves to those of Hornbeam Carpinus sp., while the common name contrasts the smooth upper surface of the leaves with those of the Wych Elm, which are rough. The tree is very susceptible to Dutch elm disease, and only a few mature trees survive in areas whither the disease has yet to spread. The tree suckers readily, and thus its genetic resources are not considered endangered.
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[edit] Cultivars
Two disease-resistant cultivars were released as part of the Dutch elm-breeding programme: Christine Buisman in 1936, and Bea Schwarz in 1948. The former was found to be very susceptible to Coral spot fungus Nectria cinnabarina and the latter grew poorly; both were soon dropped. Several others found more enduring popularity, including Hoersholmiensis and Variegata (Variegated Smooth-leaved Elm).
[edit] Hybrids
The tree's natural range generously overlaps that of Wych Elm Ulmus glabra to the north, and readily hybridizes with it to produce the so-called 'Dutch Elm' Ulmus x hollandica, while in Spain it has also naturally hybridized with the Siberian Elm U. pumila introduced in the 16th century. The tree has also featured strongly in artificial hybridization experiments in Europe and to a lesser extent in the USA. Most of the European research was based at Wageningen in the Netherlands until 1992, whence a number of hybrid cultivars have been commercially released since 1960. 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. All the commercially-released trees are listed under 'Hybrids' on the Elm species, varieties, cultivars and hybrids page.
[edit] Notable trees
A tree over 650 years old survives in the centre of Biscarrosse south of Bordeaux. Isolated amidst the heaths and pine forests of the Landes, it has remained undiscovered by disease-carrying beetles. The tree is now a wreck; the trunk, almost 3m in diameter, is completely hollow and supports just a few heavily pollarded branches[1].
[edit] References
- Armstrong, J. V. & Sell, P. D. (1996). A revision of the British elms (Ulmus L., Ulmaceae): the historical background. Bot. J. Linn. Soc. 120: 39-50.
- 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 and Disease Management. Kluwer Academic Publishers, Boston, USA.
- Heybroek, H. (1993). The Dutch elm breeding program. In Sticklen, M. & Sherald, J. (Eds). Dutch Elm Disease Research. Cellular and Molecular Approaches. Springer-Verlag, New York.
- Richens, R. H. (1983). Elm. Cambridge University Press.
- Stace, C. A. (1997). New Flora of the British Isles, 2nd edition. Cambridge University Press.
- White, J. & More, D. (2003). Trees of Britain & Northern Europe. Cassell's, London.
