Ulmus 'Nanguen'

''Ulmus'' 'Nanguen' (selling name ) is a complex fourth generation Dutch hybrid cultivar raised at the Dorschkamp Research Institute for Forestry & Landscape Planning, Wageningen. was derived from the cross 'Plantyn' × ( 'Bea Schwarz' selfed lone '336', an ancestry comprising four field elms (''U. minor''), a wych elm (''U. glabra''), the curious Exeter Elm ('Exoniensis'), and a frost-resistant selection of the Himalayan elm (''U. wallichiana''). Butterfly Conservation (2023). ''Disease-resistant elm cultivars'

Butterfly Conservation, Lulworth, England.

Originally identified as clone '812', was not promoted by the Dutch owing to unfounded fears that it may prove susceptible to coral spot fungus (''Nectria cinnabarina''). Instead, patent for '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 release in 2002 as 'Nanguen' = .
has been deemed the modern cultivar most closely resembling the native European elms.Hillier, J. G. & Lancaster, R. (Eds). (2014). ''The Hillier Manual of Trees and Shrubs'', 8th revised edition. Royal Horticultural Society; London.

Unlicenced propagation of is prohibited under Certificat d'Obtention Végétale (COV) EU 17197 until its expiry on 31 December 2036.

Description

The stem of typically forks at a height of 1–2 m, where 3–5 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 remain unknown but, given its ancestry, it should make a large tree.Johnson, H. (2010). ''Trees''. London: Mitchell Beazley. 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.
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. The leaves are elliptic to orbicular < 11 cm long × 9 cm wide, the acuminate apex far less pronounced than in most other elms, with coarse, doubly serrate margins; the upper surface is rough. The leaves flush relatively late, rarely before mid-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.

File:LUTECE in winter.jpg, LUTECE in winter
File:Ulmus LUTECE 2013.jpg, 12 year-old
File:Lutece leaves, Horsea1.jpg, leaves in July
File:Lutece leaf 2.jpg, leaf in August
File:Ulmus LUTECE samarae.jpg, samarae
File:Bark of Dutch hybrid elm Ulmus 'Nanguen' = LUTECE.jpg, Bark of 22-year-old tree
File:LUTECE suckering, Nelson Reservoir 3 (2).jpg, root suckering, Ports Down, UK

Pests and diseases

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.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. Tests in France by INRA confirmed the tree as 'highly resistant'.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. Used as a control in IRSTEA's trials of French ''Ulmus minor'' clones, it was noted that not one specimen succumbed to natural infection by DED.

Cultivation

The cultivar is now being widely planted in cities, notably Paris, and rural areas of France. Sales in France rose to almost 30,000 per annum in 2022. Pinon, J. (2023). Le retour des Ormes dans les villes françaises. ''Revue forestière française'', 74(3), 347–357. https://doi.org/10.20870/revforfr.2023.7686

was introduced to the UK by the Hampshire & Isle of Wight Branch, Butterfly Conservation, in 2001, as part of its assessment of DED-resistant cultivars as potential hosts of the endangered White-letter Hairstreak. The plants were donated by SAPHO (Syndicate for the improvement of ornamental horticultural plants) ahead of its release to commerce. In trials in southern England, the tree has proven very hardy, tolerant of sea winds, summer droughts, and ground waterlogged during winter. is cold hardy, and has survived winter temperatures as low as −30° C in Sweden.
Two lines of ten stand at Wrest Park, Bedfordshire.Tim Richardson, 'Can we resurrect the English elm?', ''The Daily Telegraph'', 6 March 2021 Among urban introductions in the UK are three specimens, planted in 2014, at the west end of Broad Walk, Christ Church Meadow, Oxford, and three in Princes Street Gardens, Edinburgh.

was introduced to North America in 2010, with the supply of two small specimens to the USDA, Washington, D.C., released from quarantine in 2013. is not known to have been introduced to Australasia.

Increasing by softwood cuttings is relatively straightforward, however these lose their viability as the donor trees mature. Several French nurseries resorted to grafting onto 'Sapporo Autumn Gold' rootstocks, but this practice ended in 2022.

File:Rue Général Léry - Annet-sur-Marne (FR77) - 2022-10-16 - 1.jpg, Twenty-two , Rue Général Léry, Annet-sur-Marne (2022), planted 2012
File:Station Porte Choisy Tramway IdF Ligne 9 - Paris XIII (FR75) - 2022-07-07 - 1.jpg, , Tramway T9 stop, Porte de Choisy station, Paris (2022)choisyleroi.fr/a-votre-service/plan-de-replantation/ Plan de replantation, Choisy
File:Station Porte Choisy Tramway IdF Ligne 9 - Paris XIII (FR75) - 2024-06-11 - 6.jpg, , Tramway T9 stop, Porte de Choisy station (2024)
File:LUTECE Towngate Newport 2.jpg, , Isle of Wight, hosting White-letter Hairstreak
File:WLH Julita.JPG, White-letter Hairstreak on , Sweden

Natural hybridization

The flowering period of coincides in part with that of field elm, and the seeds harvested have produced viable seedlings, though possibly selfed.

Conservation role

3,500 were planted on the Isle of Wight b
Natural Enterprise
and in smaller numbers in Hampshire by Butterfly Conservation and the Forestry Commission, in the hope the tree would host the white-letter hairstreak butterfly (''Satyrium w-album''), a monophagic species which remains in serious decline as a consequence of Dutch elm disease. This was confirmed in 2015 with the discovery of the butterfly breeding on specimens planted in 2003 at Towngate, Newport, Isle of Wight (see photo 5 in Gallery) and at Great Fontley in 2021 .

Etymology

The registered cultivar name 'Nanguen' is a contraction of Nancy and Wagueningen, the locations of the French and Dutch research institutes. The selling name is the French derivation of Lutetia, the ancient Roman name for the settlement which later became Paris. The name was adopted in recognition of the trials of the cultivar conducted by INRA in the Bois de Vincennes.

Accessions

Europe

*Brighton & Hove City Council, UK. NCCPG Elm Collection. Stanmer Nursery.
*Grange Farm Arboretum, Sutton St James, Spalding, Lincolnshire, UK. Acc. no. not known.
*Great Fontley Farm, Fareham, UK. ''Butterfly Conservation'' Elm Trials plantation, Home Field and the Platt, five small whips donated by SAPHO in 2002.
*Longstock Parkbr>Leckford Estate, Hampshire , Farm Produce , The Waitrose Farm
Arboretum, UK. One juvenile specimen planted 2010.
*Royal Botanic Garden Edinburgh, UK. Acc. no. 20042084
*Sir Harold Hillier Gardens, UK. Acc. no. 2004.0515
*Wijdemeren City Council, Netherlands. Elm collection. Used in elm trials Ankeveen 2009.

North America

* National Arboretum, Washington, D.C., US. Two small trees imported in 2010.

Nurseries

;Europe
*Batouwe Boomkwekerijen B.V
Batouwe boomkwekerijen BV
Dodewaard, Netherlands. Potted whips.
*F P Matthews 'Trees for Life
Ulmus LUTECE ('Nanguen')
Tenbury Wells, Worcestershire, UK. Potted trees, not grafted, propagated under licence.
*Les Pépiniéres Minie

(UK: [e-mail]), Beaufort-en-Vallée

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