[[(U. glabra var Exoniensis x U. wallichiana) x (U. minor 1 x U. minor 28)] x [(U. hollandica “Bea Schwarz” x U. hollandica “Bea Schwarz” selfed)]]
Institut National de la Recherche Agronomique, France
Lutece was developed by the Netherlands elm breeding programme but later acquired by the French agency INRA and released in 2002 after lengthy trials. It results from the crossing of the Dutch clone “Plantyn”, much used for hybridising in both the Netherlands and Italian programmes, with an early Dutch hybrid. The only non-European element in its complex ancestry is the one-sixth measure of Himalayan elm. Lutece has become the most widely planted of the modern hybrids in Britain through the efforts of Butterfly Conservation and the Island 2000 Trust on the Isle of Wight.
On the French/Dutch scale of resistance the performance of Lutece is rated 5/5. The clone was tested in the course of the Italian elm breeding programme and showed 19.75% of defoliation and 11.70% of dieback following inoculation, bettered by several of the Italian clones, but seeming to amount to effective field resistance. There are no reported cases of Lutece dying from elm disease.
Lutece forks at an early age to produce several steeply ascending branches; these continue to bifurcate, so that the tree is not naturally monopodial. Its ultimate shape can be expected to evidence the proportion of U x hollandica in its make-up, although the stouter twigs of Lutece may give it a stiffer and less rustic appearance than the Dutch elm. Its rate of growth is modest by the standard of hybrid elms. Notwithstanding that, the rootstock develops too slowly to provide ideal stability during the plant’s early years, and prolonged staking has been necessary to avoid wind-blow. Bark remains smooth longer than that of most European elms, and the tree has not been reported to sucker. It tolerates a variety of soils.
The leaves of Lutece on non-vigorous shoots are very close to those of European field elms, as would be expected from its ancestry. Leaves from near the base of such shoots are often nearly round, which is subjectively considered a desirable characteristic. Leaves on vigorous shoots show some twisting of the tips and highly developed toothing giving almost a tasselled appearance (the photograph above shows this in an extreme form). These features derive from the U. glabra “Exoniensis” (Exeter elm) component in the clone. Lutece has acquired very late leafing from its ancestor U. wallichiana; budburst is not until May in southern England, as late as the native ash. The foliage is mid-green, briefly turning deep yellow in autumn.
Lutece looks at home in a hedgerow, but it lacks charm. More specifically, it is without the vigour, richly dark colour, impressive bark and inherent sense of direction of the best European elms or a very few of the newer hybrids. Its prolonged dormancy in spring probably prevents it from becoming the resource for the White-letter Hairstreak butterfly that it was once hoped to be. These defects aside, there is no arguing with its satisfactory disease resistance or the ease with which it can be obtained in small sizes from French nurseries. For those reasons it may continue to be a useful tree.