Ulmus 'Morton'

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Ulmus 'Morton'
Morton accolade elm.jpg
Accolade, Morton Arboretum, Illinois
Genus Ulmus
Hybrid parentage U. davidiana var. japonica × U. davidiana var. japonica
Cultivar 'Morton' = Accolade
OriginUS

Ulmus 'Morton' (selling name Accolade) is an elm cultivar cloned from a putative intraspecific 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 believed to have been a hybrid of the Japanese elm (Ulmus davidiana var. japonica) and Wilson's elm (formerly Ulmus wilsoniana, but also sunk as U. davidiana var. japonica). [1] Accolade has proven to be the most successful cultivar tested in the US National Elm Trial, averaging a survival rate of 92.5% overall. [2] It had also become the most commonly planted elm in the US by 2023.

Contents

Description

The parent tree at the Morton Arboretum is noted for the resemblance of its habit to the American elm Ulmus americana, its upright-arching branches creating the familiar vase-shape, although the tree does not grow as large as the iconic native elm, reaching scarcely 20 m at maturity. [3] Its glossy, deep green leaves are also markedly smaller, rarely exceeding 8 cm in length. The tree is commercially propagated by grafting onto an Ulmus pumila rootstock.

Accolade has a propensity to produce co-dominant stems and major branches with bark inclusions, demanding corrective pruning on at least an annual basis where planted in towns. [4]

Pests and diseases

In its 90+ years, the original tree at Morton has survived three epidemics of Dutch elm disease there unscathed. [5] However, two trees included in trials at the University of Minnesota were found to be afflicted by the disease in 2004, although one appears to have recovered completely. [6] The cultivar has also proved to be highly resistant to elm yellows and the elm leaf beetle Xanthogaleruca luteola [7] , but not to the Japanese beetle, which can cause extensive foliar damage. [8]

Cultivation

Accolade is reputed to grow well in almost all soils save those excessively wet, and is notably drought-tolerant and cold hardy. In artificial freezing tests at the Morton Arboretum [9] the LT50 (temp. at which 50% of tissues die) was found to be −35.5 °C. 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 14 m in height with a crown about 5 m in width. [10] Trees grown by Tollgate Education, Michigan State University, at Novi were the most vigorous and robust of the 37 different cultivars and species under assessment, described as looking like 'men among boys'. [11] Accolade is being evaluated in the National Elm Trial [12] coordinated by Colorado State University. Accolade was introduced to Europe in 2006 and is now in commerce in the Netherlands.

Hybrid cultivars

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.

Synonymy

Accessions

North America
Europe

Nurseries

North America
Europe

Related Research Articles

<i>Ulmus davidiana <span style="font-style:normal;">var.</span> japonica</i> Variety of tree

Ulmus davidiana var. japonica, the Japanese elm, is one of the larger and more graceful Asiatic elms, endemic to much of continental northeast Asia and Japan, where it grows in swamp forest on young alluvial soils, although much of this habitat has now been lost to intensive rice cultivation.

<i>Ulmus laciniata</i> Species of tree

Ulmus laciniata(Trautv.) Mayr, known variously as the Manchurian, cut-leaf, or lobed elm, is a deciduous tree native to the humid ravine forests of Japan, Korea, northern China, eastern Siberia and Sakhalin, growing alongside Cercidiphyllum japonicum, Aesculus turbinata, and Pterocarya rhoifolia, at elevations of 700–2200 m, though sometimes lower in more northern latitudes, notably in Hokkaido.

<i>Ulmus macrocarpa</i> Species of tree

Ulmus macrocarpaHance, the large-fruited elm, is a deciduous tree or large shrub endemic to the Far East excluding Japan. It is notable for its tolerance of drought and extreme cold and is the predominant vegetation on the dunes of the Khorchin sandy lands in the Jilin province of north-eastern China, making a small tree at the base of the dunes, and a shrub at the top.

<i>Ulmus davidiana</i> Species of tree

Ulmus davidiana, also known as the David elm, or Father David elm, is a small deciduous tree widely distributed across China, Mongolia, Korea, Siberia, and Japan, where it is found in wetlands along streams at elevations of 2000–2300 m (6,500–7,500 ft). The tree was first described in 1873 from the hills north of Beijing, China.

Ulmus pseudopropinquaWang & Li, occasionally known in the United States as the Harbin spring elm, is a small deciduous tree found only in Heilongjiang, the northeasternmost province in China. The tree has not been studied comprehensively, and it has been speculated it may be a natural hybrid of Ulmus davidiana var. japonica and Ulmus macrocarpa.

<i>Ulmus szechuanica</i> Species of tree

Ulmus szechuanicaFang, known as the Szechuan (Sichuan), or red-fruited, elm, is a small to medium deciduous Chinese tree found along the Yangtze river through the provinces of Sichuan, Jiangxi, Anhui, and Jiangsu.

<i>Ulmus</i> Frontier Elm cultivar

Ulmus 'Frontier' is an American hybrid cultivar, a United States National Arboretum introduction derived from a crossing of the European Field Elm Ulmus minor with the Chinese Elm Ulmus parvifolia in 1971. Released in 1990, the tree is a rare example of the hybridization of spring- and autumn-flowering elms. Tested in the US National Elm Trial coordinated by Colorado State University, 'Frontier' averaged a survival rate of 74% after 10 years.

<i>Ulmus</i> Homestead Elm cultivar

Ulmus 'Homestead' is an American hybrid elm cultivar raised by Alden Townsend of the United States National Arboretum at the Nursery Crops Laboratory in Delaware, Ohio. The cultivar arose from a 1970 crossing of the Siberian Elm Ulmus pumila with the hybrid N 215, the latter grown from seed sent in 1960 to the University of Wisconsin-Madison elm breeding team by Hans Heybroek of the De Dorschkamp Research Institute in the Netherlands. Tested in the US National Elm Trial coordinated by Colorado State University, 'Homestead' averaged a survival rate of 85% after 10 years in the US National Elm Trial. However, planting of the tree was not recommended, owing principally to its 'ugly' shape and susceptibility to Southwest injury. 'Homestead' was released to commerce without patent restrictions in 1984.

<i>Ulmus</i> × <i>hollandica</i> Pioneer Elm cultivar

The hybrid elm cultivar Ulmus × hollandica 'Pioneer' is an American clone arising from the crossing of two European species, Wych Elm U. glabra and Field Elm U. minor. Raised by the USDA station at Delaware, Ohio, in 1971, 'Pioneer' was released to commerce in 1983.

<i>Ulmus gaussenii</i> Species of tree

Ulmus gausseniiW. C. Cheng, the Anhui, or hairy, elm, is a medium size deciduous tree whose natural range is restricted to the valleys of the Langya limestone mountains of Chu Xian in Anhui Province, eastern China. The tree was most commonly found on the flood plains, indicating a tolerance of periodic inundation. However, U. gaussenii is now possibly the rarest and most endangered elm species, with only approximately 30 trees known to survive in the wild in 2009.

<i>Ulmus</i> Morton Glossy Elm cultivar

Ulmus 'Morton Glossy' is a hybrid cultivar raised by the Morton Arboretum, Illinois. Originally named 'Charisma' until it was realized that name had already been registered for another plant, the tree was derived from a crossing of two other hybrid cultivars grown at the Morton: Accolade and Vanguard. Tested in the US National Elm Trial coordinated by Colorado State University, Triumph averaged a survival rate of 86% after 10 years. Triumph was introduced to the UK in 2006 by the Frank P. Matthews nursery in Worcestershire.

Ulmus 'Morton Plainsman' is a hybrid cultivar raised by the Morton Arboretum from a crossing of Siberian Elm and a Japanese Elm grown from openly pollinated seed donated by the Agriculture Canada Research Station at Morden, Manitoba. Tested in the US National Elm Trial coordinated by Colorado State University, Vanguard averaged a survival rate of 78% after 10 years.

<i>Ulmus</i> Morton Red Tip Elm cultivar

Ulmus 'Morton Red Tip' is a hybrid cultivar raised by the Morton Arboretum from an open pollination of Ulmus 'Morton'. The tree has occasionally been reported as a hybrid of Accolade with the Siberian Elm Ulmus pumila, an error probably owing to the commercial propagation of the tree by grafting onto U. pumila rootstocks. Tested in the US National Elm Trial coordinated by Colorado State University, Danada Charm averaged a survival rate of 77.5% after 10 years.

<i>Ulmus</i> Morton Stalwart Elm cultivar

Ulmus 'Morton Stalwart', is a Morton Arboretum hybrid cultivar arising from a controlled crossing of Accolade with the hybrid of a Field Elm U. minor from eastern Russia and a Siberian Elm U. pumila. Tested in the US National Elm Trial coordinated by Colorado State University, Commendation averaged a survival rate of 85% after 10 years.

<i>Ulmus americana</i> Princeton American elm cultivar

The American Elm cultivar Ulmus americana 'Princeton' was originally selected in 1922 by New Jersey nurseryman William Flemer of Princeton Nurseries for its aesthetic merit. 'Princeton' was later found to have a moderate resistance to Dutch elm disease (DED).

<i>Ulmus americana</i> Valley Forge Elm cultivar

The American Elm cultivar Ulmus americana 'Valley Forge' was raised by the Agricultural Research Service in Maryland. The tree was released to wholesale nurseries without patent restrictions by the U. S. National Arboretum in 1995 after proving to have a high resistance to Dutch elm disease. 'Valley Forge' proved only moderately successful in the US National Elm Trial, averaging a survival rate of 66.7% overall, owing largely to environmental factors rather than susceptibility to disease.

<i>Ulmus americana</i> New Harmony Elm cultivar

The American elm cultivar Ulmus americana 'New Harmony' was raised by the Maryland Agricultural Research Service and released by the United States National Arboretum in 1995, along with 'Valley Forge'. 'New Harmony' proved the most successful U. americana cultivar in the US National Elm Trial, averaging a survival rate of 85.5% overall.

<i>Ulmus davidiana</i> var. <i>japonica</i> Prospector Elm cultivar

The Japanese elm cultivar Ulmus davidianavar.japonica 'Prospector' was originally treated as a cultivar of Wilson's elm U. wilsonianaSchneid., a species sunk as Ulmus davidiana var. japonica by Fu. A U.S. National Arboretum introduction, it was selected in 1975 from a batch of 1965 seedlings in Delaware, Ohio, and released without patent restrictions in 1990. 'Prospector' proved moderately successful in the US National Elm Trial, averaging a survival rate of 76% overall.

<i>Ulmus</i> Patriot Elm cultivar

Ulmus 'Patriot' is a hybrid cultivar raised by the United States National Arboretum in 1980. Derived from a crossing of the American hybrid 'Urban' with the Wilson's Elm cultivar 'Prospector', 'Patriot' was released to commerce, free of patent restrictions, in 1993. Tested in the US National Elm Trial coordinated by Colorado State University, 'Patriot' averaged a survival rate of 85% after 10 years.

References

  1. ↑ Fu, L.; Xin, Y.; Whittemore, A. (2002). "Ulmaceae, in Wu, Z. & Raven, P. (eds)" (PDF). Flora of China. 5. Science Press, Beijing, and Missouri Botanical Garden Press, St. Louis, USA. (Ulmaceae through Basellaceae)
  2. ↑ Griffin, J.; et al. (2017). "Ten-Year Performance of the United States National Elm Trial" (PDF). Arboriculture & Urban Forestry. 43(3):107–120. International Society of Arboriculture, Atlanta, US.
  3. 1 2 "Accolade Elm - Ulmus x 'Accolade'". Cirrusimage.com. Retrieved 20 December 2018.
  4. ↑ Iles, J. (2009). Forget your fear of the elms. Western University website
  5. ↑ Ware, G. Morton Arb. Quarterly, 28(1): 1–5, 1992.
  6. ↑ Giblin, C. P. & Gillman, J. H. (2006). Elms for the Twin Cities: A Guide for Selection and Maintenance. University of Minnesota.
  7. ↑ McPherson, G. et al. (2008). National elm trial: Initial report from Northern California. Western Arborist, Fall 2009, 32–36.
  8. ↑ Brady, C., Condra, J., & Potter, D. (2008) Resistance of Landscape-suitable Elm (Ulmus spp.) Cultivars to Japanese Beetle, Leaf Miners, and Gall Makers. 2008 Research Report, Nursery & Landscape Program, 15–16. University of Kentucky.
  9. ↑ Shirazi, A. M. & Ware, G. H. (2004). Evaluation of New Elms from China for Cold Hardiness in Northern Latitudes. International Symposium on Asian Plant Diversity & Systematics 2004, Sakura, Japan.
  10. ↑ Guries, R. P. & Smalley, E. B., (1986), Proc. Third Nat. Urban Forestry Conf., 214–218, 1986, Orlando, Florida.
  11. ↑ "Thinking of ash alternatives? Don't forget about elms". MSU Extension. Retrieved 20 December 2018.
  12. ↑ "National Elm Trial". 26 February 2008. Archived from the original on 26 February 2008. Retrieved 20 December 2018.
  13. ↑ "The Dawes Arboretum - Newark, Ohio". 25 October 2007. Archived from the original on 25 October 2007. Retrieved 20 December 2018.
  14. ↑ "Accolade". Archived from the original on 24 March 2012. Retrieved 20 December 2018.
  15. ↑ "Photograph of autumn colouring of young 'Accolade' elms before Suzzallo Library: Arthur Lee Jacobson, 'Plant of the Month, 2008'". Arthurleej.com. Retrieved 20 December 2018.
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