The last Dutch hybrid to be released, Lutèce ™ is a complex fourth generation tree with an ancestry comprising four varieties of Field Elm U. minor, three varieties of Wych Elm U. glabra, (including the curious 'Exeter Elm', var. Exoniensis), and a frost-resistant selection of the Himalayan Elm U. wallichiana. Originally known simply as 'No. 812', it proved immune to Dutch elm disease when inoculated with unnaturally high doses of the causal fungus Ophiostoma novo-ulmi. Unlike its immediate predecessor 'Columella', it also developed a more natural, rounded shape similar to the native Field Elm.

The patent for '812' was purchased by the French Institut Nationale pour la Recherche Agronomique (INRA), which subjected the tree to 20 years of field trials in the Bois de Vincennes, Paris, before releasing it for sale in 2002 as 'Lutèce', the French derivation of Lutetia, the ancient Roman name for the settlement that later became the capital of France.

In trials in southern England, the tree has proven very hardy, tolerant of sea winds and ground waterlogged during winter. Fast growing on moist, well-drained soils, gaining an average of 80cm per annum, it commences flowering in late March when aged six years. The rounded, coarsely-toothed leaves appear relatively late, in early May, and are up to 10cm long, bright green, with a rough upper surface. Not yet 30 years old, the ultimate size of the hybrid remains unknown but, given its ancestry, should reach at least 30m in height.

Lutèce ™ is now being rapidly established in hedgerows across France. In England, over 3000 have been planted on the Isle of Wight by the Island2000 Trust, and in lower concentrations on the mainland, where it is hoped it will host the White-letter Hairstreak butterfly Satyrium w-album, a monophagic species that remains in serious decline as a consequence of Dutch elm disease. The tree is not yet (2006) available in North America.

References

• Brookes, A. H. (2006). An evaluation of disease-resistant hybrid and exotic elms as larval host plants for the White-letter Hairstreak Satyrium w-album, Part 1. Butterfly Conservation. Lulworth, UK.
• Pinon, J. (1997). New hope for elm trees (in French). Technologies France, No. 39. ADIT. France.