Ulmus 'Regal'

Ulmus 'Regal' is an American hybrid elm cultivar developed by the University of Wisconsin–Madison and released in 1983. 'Regal' was derived from seeds arising from the crossing of the Dutch hybrid clones 'Commelin' and '215' (Ulmus pumila × 'Hoersholmiensis') sent in 1960 by Hans M. Heybroek of the Dorschkamp Research Institute for Forestry & Landscape Planning, Wageningen, Netherlands.

Ulmus 'Regal'
'Regal', Dortmund.
GenusUlmus
Hybrid parentage'Commelin' × '215' (U. pumila × 'Hoersholmiensis')
Cultivar'Regal'
OriginUS

Description

'Regal' has a strong central leader bestowing an upright columnar form similar to 'Commelin', making it particularly suitable for street planting.[1][2] The foliage is distinctively sparse, allowing dappled sunlight beneath the canopy . The leaves are narrowly elliptical, 5 cm to 10 cm in length, fern green when young, changing to a glossy, trichome-free, dusky spinach green.[2] The perfect, wind-pollinated apetalous flowers emerge in early March.

  • 'Regal' leaves
  • 'Regal' foliage
  • 'Regal' bole

Pests and diseases

'Regal' has a good resistance, rated 4 out of 5,[3] to Dutch elm disease [4] and verticillium wilt, but is very susceptible to the Elm Leaf Beetle Xanthogaleruca luteola in the United States. The tree's foliage was adjudged 'resistant' to Black Spot by the Plant Diagnostic Clinic of the University of Missouri .

Cultivation

The tree performed particularly well in the Northern Arizona University trials where, along with 'Frontier', it proved very tolerant of the hot and arid conditions in the eastern part of Arizona, exhibiting minimal leaf scorch. In Europe, 'Regal' was introduced by the now-defunct Conrad-Appel nursery in Darmstadt and grown under licence by several Dutch and German nurseries as one of the Resista series . It has enjoyed modest success in Germany as a street tree , but remains uncommon in the UK, where it was introduced by the Conservation Foundation and marketed for a few years by Crowder's Nursery, near Lincoln. 'Regal' was planted in the Royal Horticultural Society's garden at Harlow Carr, North Yorkshire.[5] It was trialled by Edinburgh Council, and many healthy specimens survive in the city.[6] 'Regal' also featured in trials in New Zealand during the 1990s at the Hortresearch station, Palmerston North.

  • 'Regal', Craigleith Rd, Edinburgh
  • 'Regal' along a German highway
  • Elm cultivars, Nether-lands; 'Regal' 2nd from left
  • 'Regal' in Daleview Gardens, Hove (2008)

Notable trees

The UK TROBI champion is at Abbey Park, Leicester, measuring 14 m high, 26 cm d.b.h. in 2004.

Hybrid cultivars

Accessions

North America

Europe

Nurseries
North America
Europe

References
  1. Santamour, J., Frank, S. & Bentz, S. (1995). Updated checklist of elm (Ulmus) cultivars for use in North America. Journal of Arboriculture, 21:3 (May 1995), 121–131. International Society of Arboriculture, Champaign, Illinois, US.
  2. Smalley, E. B. & Lester, D. T. (1983), HortScience 18: 960–961, 1983.
  3. 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
  4. Burdekin, D.A.; Rushforth, K.D. (November 1996). Revised by J.F. Webber. "Elms resistant to Dutch elm disease" (PDF). Arboriculture Research Note. Alice Holt Lodge, Farnham: Arboricultural Advisory & Information Service. 2/96: 1–9. ISSN 1362-5128. Retrieved 26 October 2017.
  5. Katherine Swift, The Times, 7 June 2003
  6. 'Regal' in Edinburgh: nomorepencils.com/dutch-elm-disease-in-edinburgh/; fombl.org.uk/nl4.pdf; fombl.org.uk/nl5.pdf
  7. "List of plants in the {elm} collection". Brighton & Hove City Council. Retrieved 23 September 2016.
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