Ulmus 'Nanguen' = Lutece

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Ulmus hybrid
Ulmus LUTECE 2013.jpg
Lutèce aged 12 years, Great Fontley, UK
Hybrid parentage 'Plantyn' × ('Bea Schwarz' × 'Bea Schwarz' selfed)
Cultivar 'Nanguen' = Lutece
Origin Wageningen, The Netherlands

One of the last Dutch hybrid cultivar elms to be released, Ulmus 'Nanguen' (selling name Lutèce) is a complex fourth generation tree from the cross 'Plantyn' × (U. hollandica 'Bea Schwarz' selfed), an ancestry comprising four Field Elms U. minor, three Wych Elms U. glabra including the curious Exeter Elm, var. 'Exoniensis', and a frost-resistant selection of the Himalayan Elm U. wallichiana.

Originally identified as clone 812, Lutèce was not promoted by the Dutch owing to unfounded fears that it may prove susceptible to Coral Spot fungus Nectria cinnabarina. Instead, '812' was acquired by the French Institut National de la Recherche Agronomique (INRA), which subjected the tree to 20 years of field trials in the Bois de Vincennes, Paris, before patenting and release in 2002 as 'Nanguen' = Lutèce.[1][2]

Description[edit]

The stem of Lutèce typically forks at a height of between 1 and 2 m, where 3 to 5 steeply ascending branches develop in conjunction with more obtusely angled lower side branches to form an amorphous open crown. The ultimate size and shape of this cultivar remains unknown but, given its ancestry, it should reach at least 30 m in height. The trees planted in the Bois de Vincennes attained an average height of 12.5 m with a trunk diameter of 22 cm at 20 years of age.[3] Quick growing on moist, well-drained soils, increasing in height by an average of 80 cm per annum, the tree commences flowering in late March when aged seven years.

Lutèce is most reliably identified by the shape and colour of its leaves; elliptic to orbicular < 11 cm long × 9 cm wide, the acuminate apex far less pronounced than in most other elms, and coarse, doubly-serrate margins. The upper surface is rough, and bright grass-green in colour. The leaves flush relatively late, rarely before May in England. The samarae are obovate, slightly notched at the outer end, 14 – 22 mm long by 11 – 17 mm broad. The seed is not central but slightly nearer the notch, and ripens in late May.[4]

Pests and diseases[edit]

Lutèce exhibited a high resistance to Dutch elm disease when inoculated with unnaturally high doses of the causal fungus Ophiostoma novo-ulmi, and was rated 5 out of 5 in Dutch tests.[5] Tests in France by INRA confirmed the tree has 'highly resistant'.[3] [6] In trials conducted by the Istituto per la Protezione delle Piante, Florence, Lutèce suffered 19.8% defoliation and 11.7% dieback when inoculated, compared with 2.8% and 1.2% resp. for 'Sapporo Autumn Gold', and 50% and 35.5% resp. for 'Lobel'.[7][5]

The presence of U. wallichiana in the ancestry of Lutèce poses the risk of susceptibility to elm yellows (phloem necrosis), which seriously damaged its Dutch stablemate 'Lobel' used as a control in the Italian elm breeding programme.[8]

Cultivation[edit]

The cultivar is now being widely planted in cities, notably Paris, and rural areas of France.[9] In trials in southern England, the tree has proven very hardy, tolerant of sea winds, summer droughts, and ground waterlogged during winter. However, some trees proved susceptible to wind-rock and have required staking for up to six years. Lutèce is cold hardy, and has survived winter temperatures as low as - 30° C at Julita in Sweden.[4]

Over 4000 Lutèce have been planted on the Isle of Wight by the Island 2000 Trust, and in lower concentrations on the mainland, mostly by Butterfly Conservation and the Forestry Commission in the hope the tree will host the White-letter Hairstreak butterfly Satyrium w-album, a monophagic species which remains in serious decline as a consequence of Dutch elm disease[4] Lutèce was introduced to North America in 2010, with the arrival of two small specimens at the National Arboretum, Washington, D.C.; it is not known to have been introduced to Australasia.

Etymology[edit]

Lutèce is the French derivation of Lutetia, the ancient Roman name for the settlement which later became Paris.

Accessions[edit]

Europe[edit]

North America[edit]

Nurseries[edit]

Europe

References[edit]

  1. ^ SAPHO. Ulmus 'Nanguen' = Lutèce, [1], La Menitre, France.
  2. ^ Department of Forest Health, Forest Health in France 2002 [2], Paris, France.
  3. ^ a b Pinon, J. 2007). Les ormes résistants à la graphiose (:Elms resistant to Dutch Elm Disease). Forêt-entreprise, No. 175 - Juillet 2007, p 37-41, IDF, Paris, France. http://www.foretpriveefrancaise.com/data/info/127219-P.pdf
  4. ^ a b c Brookes, A. H. (2012). Disease-resistant elm cultivars, Butterfly Conservation trials report, 2nd revision, 2012. Butterfly Conservation, Hants & IoW Branch, England. [3]
  5. ^ Heybroek, H. M., Goudzwaard, L, Kaljee, H. (2009). Iep of olm, karakterboom van de Lage Landen (:Elm, a tree with character of the Low Countries). KNNV, Uitgeverij. ISBN 9789050112819
  6. ^ Pinon, J., Lohou, C. & Cadic, A. (1998). Hybrid Elms (Ulmus Spp.): Adaptability in Paris and behaviour towards Dutch elm disease (Ophiostoma novo-ulmi). Acta Horticulturae 496, 107-114, 1998.
  7. ^ Santini, A, et al. (2002). 'San Zanobi' and 'Plinio' Elm trees. HortScience 37(7): 1139–1141, 2002.
  8. ^ Mittempergher, L., (2000). Elm Yellows in Europe. In: The Elms, Conservation and Disease Management. pp.103-119. Dunn C.P., ed. Kluwer Academic Press Publishers, Boston, USA.
  9. ^ Institut National de la Recherche Agronomique. Lutèce, a resistant variety brings elms back to Paris [4], Paris, France.

Pictures[edit]

Photographs of the Isle of Wight's Island 2000 Trust planting Lutece elms can be seen at the Flickr website here at [13] and [14].