ULMUS 'MORTON'

''Morton'' ('Accolade™') is an elm cultivar derived from a hybrid planted at the Morton Arboretum in 1924, which itself originated as seed collected from a tree at the Arnold Arboretum in Massachusetts. Although this tree was originally identified as ''Ulmus crassifolia'', it is now is believed to have been a hybrid of the Japanese Elm ''Ulmus davidiana'' var. ''japonica'' and Wilson's Elm, the latter now sunk as another form of ''Ulmus davidiana'' var. ''japonica'' (Fu, 2002).
The tree at the Morton Arboretum was noted for the resemblance of its habit to the American Elm ''Ulmus americana'', its upright-arching branches creating the familiar vase-shape. Moreover, in its 80+ years it had survived three epidemics of Dutch Elm Disease there unscathed. However, two trees included in trials at the University of Minnesota were found to be afflicted by the diease in 2004, although one appears to have recovered completely (Giblin & Gillman, 2006).
'Morton' has now been cloned and promoted by the Chicagoland Grows corporation as a potential substitute for the innumerable American Elms lost to disease, although the tree does not grow as large as the iconic native elm, reaching scarcely 20 m at maturity; its glossy, deep green leaves are also markedly smaller.
'Morton' is reputed to grow well in almost all soils save those excessively wet, and is notably drought-tolerant and winter hardy. The tree grows vigorously at first, gaining as much as one metre per annum, but slows to approximately half that rate with maturity. Thus, a typical 20 year-old tree could be expected to have reached 10 m in height with a crown about 5 m in width.
'Morton' has also proved to be highly resistant to elm yellows and the elm leaf beetle. It is currently being evaluated in the National Elm Trial [1] coordinated by Colorado State University.
The tree will not be commercially available in Europe until at least 2008, but specimens grown from selfed seeds are featured in the ''Butterfly Conservation'' elm trials in Hampshire, England, where they have grown with extraordinary vigour, and proven very tolerant of local conditions, notably waterlogged soils in winter.

Contents

Hybrid cultivars

Arboreta etc. accessions

North America

Europe

Nurseries

North America

Europe

Synonymy

References

External links

Hybrid cultivars

'Morton' (Accolade™) was crossed with the hybrid cultivar 'Morton Plainsman' ('Vanguard™'). A selection of the resultant seedlings was marketed under the name 'Charisma', later changed to 'Morton Glossy' (Triumph™).

Arboreta etc. accessions

North America

★ Arnold Arboretum acc. no. 130-2002

★ Bickelhaupt Arboretum acc. no. 98-051

★ Brenton Arboretum No details available.

★ Holden Arboretum acc. nos. 89-76, 91-114, 98-23, L-00-501

★ Morton Arboretum acc. nos. 2352-24, 255-74, 128-92, 272-97, 35-98, 280-2003. 495-2004, 1095-2004, 1246-2004, 1347-2004

★ Smith College acc. nos. 20304, 35804, 37505

Europe

★ Great Fontley Farm, Fareham, UK, ''Butterfly Conservation'' Elm Trials plantation, Home Field, (from seed sent from Morton Arboretum, Illinois).

★ Royal Botanic Garden Edinburgh, UK, acc. no. 20021372

Nurseries

North America

★ Acorn Farms [2], Galena, Ohio.

★ Bailey Nurseries [3], St. Paul,Minnesota.

★ Charles J. Fiore [4], Prairie View, Illinois.

★ ForestFarm [5], Williams, Oregon.

★ J. Frank Schmidt & Son Co. [6], Boring, Oregon

★ North American Plants [7], Lafayette, Oregon.

★ Pea Ridge Forest [8], Hermann, Missouri.

Europe

None known.

Synonymy

★ Thornhill Elm: Anon.

References

★ Brookes, A. H. (2006). ''An evaluation of disease-resistant hybrid and exotic elms as larval host plants for the White-letter Hairstreak butterfly Satyrium w-album'', Part 1. Butterfly Conservation, Lulworth, UK.

★ Fu, L., Xin, Y. & Whittemore, A. (2002). Ulmaceae, in Wu, Z. & Raven, P. (eds) ''Flora of China'', Vol. 5 (Ulmaceae through Basellaceae). Science Press, Beijing, and Missouri Botanical Garden Press, St. Louis, USA. [9]

★ Giblin, C. P. & Gillman, J. H. (2006). ''Elms for the Twin Cities: A Guide for Selection and Maintenance.'' University of Minnesota.

★ Guries, R. P. & Smalley, E. B., (1986), ''Proc. Third Nat. Urban Forestry Conf.'', pp 214-218, 1986, Orlando, Florida.

★ Ware, G. ''Morton Arb. Quarterly'', 28(1): 1-5, 1992.

External links

★ http://www.extension.iastate.edu/Publications/SUL4.pdf Summary, inc. photographs, of elm cultivars resistant to Dutch elm disease available in the USA.

★ http://fletcher.ces.state.nc.us/programs/nursery/metria/metria11/warren/elm.htm Warren, K., J. Frank Schmidt & Son Co. (2002). ''The Status of Elms in the Nursery Industry in 2000''.

★ http://www.mortonarb.org/plantinfo/plantclinic/phc/New-Elms-For-The-Landscape.pdf. Miller, F. (2002). ''New elms for the landscape and urban forest''.