Ulmus 'Morton Plainsman' (selling name ) is a hybrid cultivar raised by the Morton Arboretum from a crossing of Siberian Elm (female parent) 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, averaged a survival rate of 78% after 10 years.
Description has modest upright growth, increasing in height by an average of 0.8 m in an assessment at U C Davis,McPherson, G. et al. (2008). National elm trial: Initial report from Northern California. Western Arborist, Fall 2009, 32–36. with leaves much the same size and colour of the American elm. However, its performance in the southern United States has not impressed, and it was dismissed, along with its Morton stablemates and , as "ugly" by Michael Dirr, Professor of Horticulture at the University of Georgia , on account of its "wild" growth and splaying branches.
Pests and diseases Although resistant to Dutch elm disease in the US, remains very susceptible to pests such as the elm-leaf beetle Xanthogaleruca luteola , Japanese beetle,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. and cankerworms.
Cultivation In trials at the University of Minnesota, was found to have the second highest (after ) incidence of branch breakage occasioned by bark inclusions.Giblin, C. P. & Gillman, J. H. (2006). Elms for the Twin Cities: A Guide for Selection and Maintenance. University of Minnesota. However, the tree has a high degree of drought and cold tolerance making it particularly suitable for afforestation in the Great Plains.Ware, G. (1992). Morton. Arb. Quarterly 28(1): 1–5, 1992. In artificial freezing tests at the Morton ArboretumShirazi, 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. the LT50 (temp. at which 50% of tissues die) was found to be −40°C.
The tree is currently being evaluated in the National Elm Trial coordinated by Colorado State University. It is not known to have been introduced to Australasia.
Hybrid cultivars was crossed with the hybrid cultivar ; a selection from the resultant seedlings was marketed under the name 'Charisma', later changed to 'Morton Glossy' = .
Accessions North America Bartlett Tree Experts, US. Acc. nos. 2001–106, 2001-108 Brenton Arboretum, US. 5 trees, acquired 2009. Acc. no. not known. Chicago Botanic Garden, US. 2 trees, no other details available. Dawes Arboretum, Newark, Ohio, US. 1 tree, accession no. 2004-0047.001.'Morton Plainsman' = , Dawes Arboretum Holden Arboretum, US. Acc. no. 00–127 Morton Arboretum, US. Acc. nos. 273–97, 4–2004, 156–2005.Photographs of Morton Arboretum elm, Acc. no. 273-97; cirrusimage.com Smith College, US. Acc. no. 36505 University of Idaho Arboretum, US. Two trees. Acc. no. 2000093 Europe Grange Farm Arboretum, Lincolnshire, UK. Acc. no. 1139.
Nurseries North America Acorn Farms , Galena, Ohio, US. Bailey Nurseries , St. Paul, Minnesota, US. J. Frank Schmidt & Son , Boring, Oregon, US. Johnson's Nursery , Menomonee Falls, Wisconsin, US. Sun Valley Garden Centre , Eden Prairie, Minnesota, US.
References
External links 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.