U. glabra × U. minor (U. × hollandica Mill.), Dutch Elm
Account Summary
Introduced, neophyte, a deliberately planted cultivar, very rare.
1912; Druce, Dr G.C.; planted by roadsides near Enniskillen.
Fermanagh occurrence
This hybrid has only been recorded once in Co Fermanagh (as U. major Smith (= U. × hollandica Miller = U. coritana Melville × U. glabra Huds.)), by the famous English botanist Clarence Druce. The solitary Fermanagh site is simply recorded by him as, "Enniskillen, County Fermanagh" (Druce 1912), but it is worth looking out for along roads around Enniskillen, where specimens of it might well survive. Mature trees of this cultivar display somewhat greater resistance to Dutch elm disease than does Ulmus glabra (Wych Elm), our only indigenous Irish elm species.
Identification problems
Hybrid elms are very variable and difficult to unravel, and there has been very considerable, yet perfectly understandable confusion between this hybrid and U. × vegeta (Loudon) Ley, the Huntingdon elm (a single clone, and therefore a cultivar), both of whose parent species, U. glabra and U. minor (Small-leaved Elm), are shared by U. × hollandica. Although all U. x hollandica hybrids are called 'Dutch Elm' by some authorities, the cultivar 'Major' is a convenient reference to the particular type of this natural hybrid that was usually planted in England, and it also provides a horticultural distinction between Dutch Elm and the Huntingdon Elm, or indeed the Belgian Elm 'Belgica' (More & White 2003, p. 403).
In his account of this hybrid, Melville in Stace (1975) concluded that U. × hollandica (or U. × hollandica 'Major') also includes U. plotii in its ancestry, a belief indicated by the smaller leaves with blunter serrations (R. Melville, in: Hybridization; Mitchell 1996). However, in their new book on the subject Hybrid Flora of the British Isles, Stace et al. (2015) regard this opinion as rather questionable, on the grounds that U. x hollandica is known to be abundant on the Continent and U. plotii is considered endemic to England.
There has also been confusion in nomenclature, as is already indicated by the list of names given in brackets above. In his posthumously published book Trees of Britain, the English tree identification expert Alan Mitchell considered that, "The group name for the many hybrids of this origin has, of course, been a botanical plaything." And again, "…there were some half a dozen names in use before Miller’s 'hollandica' was adopted as the group name for all the Dutch elms and 'Vegeta' was placed among them." (Mitchell 1996, p. 351). The problem of elm identification is encapsulated in several statements made by Oliver Rackham. "There are arguably more kinds of elm in England than all other native trees together. Wych-elm (Ulmus glabra) is a 'normal' species; it is not clonal, grows from seed, and coppices. Clonal elms [on the other hand] generate a host of 'microspecies', rather as brambles and dandelions do. There are many intermediates and possible hybrids." (Rackham 2006, p. 29)
Irish occurrence
No thorough investigation of unusual, often small-leaved forms of Ulmus has ever been attempted in N Ireland, and very probably this is the case throughout the whole of Ireland. However, in Cat Alien Pl Ir, Reynolds mentions that on the basis of his own observations Dr D. Kelly of Trinity College Dublin shares the opinion of the English elm specialist Dr R.H. Richens, who examined the Irish situation in the 1970s. Both these authorities believe that U. × hollandica and U. minor s.s. are widely planted elms in Ireland, and that U. procera (English Elm), on the other hand, is a scarce and very local tree here. Nevertheless, the Cat Alien Pl Ir published in 2002 lists a total of only five records for U. × hollandica from three Irish VCs, with dates ranging from 1973 to 1986.
On account of the critical identification difficulties mentioned, it is not really surprising that the New Atlas shows only a couple of Irish hectads with records of U. × hollandica, and there are no records at all of U. × vegeta plotted for Ireland in the atlas. This is the case despite the fact that the Huntingdon cultivar grows very vigorously without suckering, and it displays even greater resistance to Dutch elm disease than its already fairly resistant U. glabra parent does (New Atlas).
Anyone wishing to re-establish beautiful and useful mature elms anywhere in Ireland might, in RSF's view, try planting the Huntingdon cultivar, U. × hollandica 'Vegeta', or one or more of the new disease resistant varieties being bred at present.
British occurrence
In marked contrast with the Irish situation, elms with this parentage are frequent and widespread in England and Wales and especially so in SE England. They occur in ancient woodland, roadside and streamside copses, in hedgerows and in amenity plantations in both rural and urban settings (Stace et al. 2015). A survey by Jeffers & Richens (1970) concluded that this hybrid was, along with U. glabra, U. minor and U. procera, one of the four principal constituents of the English elm flora. The hybrid is regarded as certainly commoner than U. glabra in some areas of E England where this parent is an uncommon tree, and the same applies in the Channel Isles (Stace et al. 2015).