Ulmus 'Nanguen'

Ulmus hybrid
LUTÈCE, aged 9 years, Great Fontley, UK
Details
Hybrid parentage	'Plantyn' × ('Bea Schwarz' × 'Bea Schwarz' selfed)
Cultivar	'Nanguen' = LUTÈCE ®
Origin	Wageningen, The Netherlands

One of the last Dutch hybrid cultivars to be released, 'Nanguen' (LUTÈCE) is a complex fourth generation tree with 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 simply 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' (selling name: LUTÈCE).^[1][2]

Description

The stem of LUTÈCE typically forks at a height of between 1 m 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. Not yet 30 years old (2009), the ultimate size and shape of this cultivar remain 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; almost orbicular < 11 cm long × 10 cm wide, the acuminate apex far less pronounced than in most other elms, and bright grass-green in colour, with a rough upper surface. 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].

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  LUTÈCE leaves in high summer.

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  LUTÈCE leaf, with 1 Euro coin.

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  LUTÈCE samarae.

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  White-letter Hairstreak on LUTÈCE, Julita, Sweden. Photo: Leif Wahlberg

Pests and diseases

LUTÈCE exhibited a very 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]

The leaves are susceptible to Black Spot however ^[4].

Cultivation

The cultivar is now being widely planted in cities, notably Paris, and rural areas of France.^[7] 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.

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 members of Butterfly Conservation in the hope the tree 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^[4].

LUTÈCE has been introduced to North America, with the arrival of two small specimens at the National Arboretum, Washington, D.C. in November, 2010; it is not known to have been introduced to Australasia.

Etymology

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

Accessions

Europe

• Brighton & Hove City Council, UK, NCCPG Elm Collection [5]. Stanmer Nursery.
• Great Fontley Farm, Fareham, UK, Butterfly Conservation Elm Trials plantation, Home Field B2, C2, J7, J9, Platts O10, (planted 2002).
• Longstock Park [6] Arboretum, Longstock, Stockbridge, UK. One juvenile specimen planted 2010.
• Royal Botanic Garden Edinburgh, UK. Acc. no. 20042084
• Sir Harold Hillier Gardens, UK. Acc. no. 2004.0515

North America

• National Arboretum, Washington, D.C.. 2 small trees, in quarantine until May 2011.

Nurseries

Europe

• Adrian Ayley [7], Southminster, Essex, UK. 15 and 30 litre potted standards.
• F P Matthews 'Trees for Life', Tenbury Wells, Worcestershire, UK. 7-litre pot trees available from retail outlets, see [8]
• Hilliers Nurseries [9], Ampfield, UK. Standards only.
• Les Pépiniéres Minier [10] (UK: [e-mail]), Beaufort-en-Vallée, France. Bare-rooted whips, minimum export value: €500.

References

1. ^ SAPHO. Ulmus LUTECE 'Nanguen', [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. (2010). Disease-resistant elm cultivars: Butterfly Conservation trials report, 2010. 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 9709050112819
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. ^ Institut National de la Recherche Agronomique. Lutèce, a resistant variety brings elms back to Paris [4], Paris, France.

Pictures

Photographs of the Isle of Wight's Island 2000 Trust planting Lutece elms can be seen at the Flickr website here at [11] and [12].