Ulmus × hollandica
|Ulmus × hollandica|
Ulmus × hollandica in Cambridgeshire, 2006
|Hybrid parentage||U. glabra × U. minor|
Ulmus × hollandica Mill. , often known simply as Dutch Elm, is a natural hybrid between Wych Elm Ulmus glabra and Field Elm Ulmus minor which commonly occurs across Europe wherever the ranges of the two parent species overlap. In England, according to the field-studies of R. H. Richens, "The largest area [of hybridization] is a band extending across Essex from the Hertfordshire border to southern Suffolk. The next largest is in northern Bedfordshire and adjoining parts of Northamptonshire. Comparable zones occur in Picardy and Cotentin in northern France".
F1 hybrids between Wych and Field Elm are fully fertile, but produce widely variant progeny. Many also inherit the suckering habit of their Field Elm parent. Both Richens and Rackham noted that examples in the East Anglian hybridization zone were sometimes pendulous in form. A surviving mature U. × hollandica at Actons Farm, Sawbridgeworth, Hertfordshire - if it was not, as has been suggested, a seedling of Vegeta (Huntingdon Elm) from the local Rivers Nursery (see under Vegeta) - is a case in point.
In form and foliage, the trees are broadly intermediate between the two species.
Pests and diseases
The great elm in the Grove of Magdalen College, Oxford, photographed by Henry Taunt in 1900 and said by Elwes to be the largest elm in Great Britain, was long believed to be a wych elm but was found on examination by Elwes and Henry to be a Huntingdon-type hybrid that at c.300 years old pre-dated the cultivation of Huntingdon Elm. When it blew down in 1911, by Elwes' measurements it had been 142 feet high and 27 feet in girth at five feet, and contained 2787 cubic feet of timber.
With a girth of 22 feet 6 inches (6.86 m) and a height of 40 metres, the Ulmus × hollandica hybrid elm on Great Saling Green, Great Saling, near Braintree, Essex, was reputedly the largest elm in England, before succumbing to Dutch Elm Disease in the 1980s. A photograph of the tree can be found (plate 402) in Elwes & Henry's Trees of Great Britain & Ireland  published in 1913, wherein it is identified as U. nitens (''Ulmus minor'').
Examples of mature survivors in the East Anglian hybridisation zone include the elms at the River Can weir, at the western end of Admiral's Park, Chelmsford, Essex, and those near Royston, Hertfordshire, designated 'Elm of the Year, 2004' by Das Ulmen Büro.
There are two notable TROBI Champion trees in the British Isles, one at Little Blakenham, Suffolk, measuring ? high by 160 cm d.b.h. in 2008, the other at Nounsley, Essex, 17 m high by 150 cmd.b.h. in 2005.
The hybrid elm in art
The elms in the Suffolk landscape-paintings and drawings of John Constable were "most probably East Anglian hybrid elms ... such as still grow in the same hedges" in Dedham Vale, Flatford and East Bergholt. Elm trees in Old Hall Park, East Bergholt  is often considered the finest of Constable's elm-studies.
At least 30 cultivars have been recorded, although over half have now been lost to cultivation because of Dutch elm disease:
- Arnold Arboretum. Acc. nos. 325-81, 7614, 92-38
- Bartlett Tree Experts. Acc. nos. 1245, 1246
- New York Botanical Garden. Acc. no. 508/79
- Niagara Parks Botanical Gardens. Acc. no. 940414
- Eastwoodhill Arboretum , Gisborne, New Zealand. 24 trees, details not known.
- Waite Arboretum , University of Adelaide, Adelaide, Australia. Acc. nos. 368, 339
- Richens, R. H., Elm (Cambridge 1983), p. 95, 233
- Richens, R. H. (1983), Elm
- Clouston, Brian, & Stansfield, Kathy, eds.: After the Elm (Heinemann, London, 1979)
- Oliver Rackham, A History of the Countryside (London, 1986)
- Bean, W. J. (1981). Trees and shrubs hardy in Great Britain, 7th edition. Murray, London
- Elwes, H. J. & Henry, A. (1913). The Trees of Great Britain & Ireland. Vol. VII. pp 1848-1929. Private publication, Edinburgh.
- Collin, E. (2001). Elm. In Teissier du Cros (Ed.) (2001) Forest Genetic Resources Management and Conservation. France as a case study. Ministry of Agriculture and Fisheries, Bureau of Genetic Resources. INRA DIC. France.
- Burdekin, D. A. & Rushforth, K. D. (Revised by Webber J. F. 1996). Elms resistant to Dutch elm disease. Arboricultural Research Note 2/96. Arboricultural Advisory and Information Service, Alice Holt, Farnham, UK.
- The great elm in Magdalen College, 4.bp.blogspot.com 
- Henry Taunt's photographs of the great elm in Magdalen College, viewfinder.english-heritage.org.uk 
- 1911 photograph of the great elm at Magdalen College, fallen: Maxwell, Herbert, Trees: a Woodland Notebook, Containing Observations on Certain British and Exotic Trees (Glasgow, 1915), p.55: gutenberg.org 
- R. H. Richens, Elm, p.243
- Photograph of the Great Saling Elm, carolizejansen.com 
- U. x hollandica hybrids (to judge by branching, perhaps not 'Huntingdon' clones), Burloes, near Royston, Hertfordshire, Das Ulmen Büro 'Elm of the Year, 2004', Dr. Gordon Mackenthun 
- Johnson, O. (2011). Champion Trees of Britain & Ireland, p. 169. Kew Publishing, Kew, London. ISBN 9781842464526.
- R. H. Richens, Elm, p.166, 179
- R. H. Richens, Elm, p.178
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