Ulmus × hollandica
|Ulmus × hollandica|
|Hybrid parentage||U. glabra × U. minor|
|Cultivar||Ulmus × hollandica|
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 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".
In form and foliage, the trees are broadly intermediate between the two species. 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.
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, it had been 43.7 metres (143 ft) high and 8.3 metres (27 ft) in girth and comprised an estimated 81 cubic metres (2,900 cu ft) of timber. It was considered the largest tree of any kind in Britain, and possibly the largest tree north of the Alps.
With a girth of 6.9 metres (23 ft) and a height of 40 metres (130 ft), 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 centimetres (5.2 ft) d.b.h. in 2008, the other at Nounsley, Essex, 17 metres (56 ft) high by 150 centimetres (4.9 ft) d.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
- Sir Harold Hillier Gardens, UK. Acc. no. 1977.0615
- Wijdemeren City Council, Netherlands, Elm collection. Frans Halslaan, Loosdrecht (~1960)
- 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)
- Richens, R. H., Elm (Cambridge 1983), p. 95, 233
- Richens, R. H. (1983), Elm
- 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. 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.
- Clouston, Brian, & Stansfield, Kathy, eds.: After the Elm (Heinemann, London, 1979)
- Oliver Rackham, A History of the Countryside (London, 1986)
- 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 
- Elwes, H. J. & Henry, A. (1913). The Trees of Great Britain & Ireland. Vol. VII. p.1881–1882. Republished 2004 Cambridge University Press, ISBN 9781108069380
- 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 
- Editorial, Quart. J. For. 5 (1911). 'An enormous elm'. 278–280. Royal Forestry Society.
- 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 
- Google Maps: England - Google Maps, accessdate: July 27, 2016
- 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
- R. H. Richens, Elm, p.166)
|Wikimedia Commons has media related to Ulmus × hollandica.|