Ulmus americana 'Jefferson'

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Ulmus americana 'Jefferson'
Jefferson-Washington-James-L-Sherald-300x202.jpg
The original 'Jefferson' elm on the National Mall in Washington, D.C. (March 2014)
Species Ulmus americana
Cultivar 'Jefferson'
OriginNational Park Service, US

The American Elm cultivar Ulmus americana 'Jefferson' was cloned from a tree growing near a path in front of the Freer Gallery of Art, close to the Smithsonian Institution Building ("The Castle") on the National Mall in Washington, D.C. [1] The United States National Park Service, which had planted the tree during the 1930s, cloned it in 1993 after screening tests showed that it possessed an outstanding level of tolerance to Dutch elm disease (DED). [1]

Contents

In 2005, the Park Service and the Agricultural Research Service (ARS) of the United States Department of Agriculture jointly released the clone (formerly NPS 3–487) to the nursery trade as 'Jefferson'. [1] The parent tree appears to have remained unscathed by DED in 2014.

Description

'Jefferson' is distinguished by its low, spreading form with arching limbs and broad U-shaped crotches. [2] The parent tree on the National Mall has reached a height of about 68 feet (20.7 m) after 80 years. Ploidy: 2n = 42.

Genetics

Early studies on the parent tree found that the tree has triploid chromosomes, suggesting that it may be a hybrid between the tetraploid American Elm and an unknown diploid species. [3] A genetic study that the ARS conducted on the clone at the United States National Arboretum in Washington, D. C., during 2004 confirmed the tree as Ulmus americana, despite having some atypical features. [4]

A subsequent ARS study also confirmed that the tree is a triploid. The study's investigators concluded that a crossing of two American Elms, one a tetraploid, the other a less common diploid, had created the tree. The investigators found no triploids among the 81 wild trees that they sampled. [5]

Pests and diseases

The tree proved highly resistant to Dutch elm disease in an ARS trial (as clone N 3487/NA 62001). [6] NA 62001 showed little damage from elm leaf beetle (Xanthogaleruca luteola) feeding during a 2009—2010 survey at an Oklahoma arboretum. [7] 'Jefferson' is susceptible to elm yellows phytoplasma infection, as are other U. americana DED-resistant cultivars and native trees of that species. [8]

The Japanese beetle (Popillia japonica) highly prefers U. americana when feeding. [9] Verticillium wilt had a greater effect on U. americana than it had on all other elms studied in an investigation of that fungal disease. [10]

Cultivation

President George W. Bush planting a 'Jefferson' clone outside of the White House in October 2006. President George W. Bush and Laura Bush take part in the planting of three elm trees.jpg
President George W. Bush planting a 'Jefferson' clone outside of the White House in October 2006.

'Jefferson' has not been widely tested beyond Washington D.C. National Elm Trial results were inconclusive and provided no data on ‘Jefferson’ because of an early error in tree identification that occurred in the nursery trade. [11] [12] The error may still be causing nurseries to sell 'Princeton' elms that are mislabeled as 'Jefferson', although one can distinguish between the two cultivars as the trees mature. [11] [13] The Golden Hill Nursery in Kent introduced 'Jefferson' to the United Kingdom in 2010, but the clone remains rare in cultivation.

Accessions

North America

Europe

Notes

  1. 1 2 3 (1) Flores, Alberto (June 13, 2006). "Jefferson Trees Resistant to Dutch Elm Disease". News & Events. United States Department of Agriculture: Agricultural Research Service. Archived from the original on January 26, 2021. Retrieved January 30, 2021. In 2005, the newest American elm—named Jefferson—was released jointly by ARS and the National Park Service (NPS), after collaborative screening tests by Townsend and James L. Sherald, NPS Natural Resource Officer, showed it to have an outstanding level of Dutch elm disease (DED) tolerance. It was cloned in 1993 from the original tree, a survivor of about 300 elms planted on the National Mall in Southwest Washington in the 1930s..
    (2) Bentz, S.E. (February 2005). "Mature American elm of variety "Jefferson," at the old Smithsonian building, Washington, DC". Archived from the original (photograph) on February 2, 2017. Retrieved January 30, 2021 via elmpost.org elmpost.org]..
    (3) Sherald, 2009, pp. 37—38.
  2. Sherald, 2009, p. 38. Photographs: (1) Figure 33: "American elm 'Jefferson'. Parent tree on the National Mall in front of the Freer Gallery of Art on Jefferson Drive, flanked on either side by trees vegetatively propagated from it."
    (2) Figure 34: "Young ‘Jefferson’ elms on the National Mall come into full leaf before native American elms."
  3. (1) Sherald, James L.; Santamour Jr., Frank S.; Hajela, Ravindra K.; Hajela, Neerja; Sticklen, Mariam B. (April 1, 1994). "A Dutch elm disease resistant triploid elm". Canadian Journal of Forest Research. Ottawa, Ontario: Canadian Science Publishing. 24 (4): 647–653. doi:10.1139/x94-087. ISSN   1208-6037. LCCN   71618428. OCLC   969764715 . Retrieved January 30, 2021.
    (2) Warren, Keith (August 21, 2000). "American Elm Cultivars - Ulmus americana: Ulmus americana 'Jefferson': Jefferson Elm". Return of the Elm: The Status of Elms in the Nursery Industry in 2000. J. Frank Schmidt & Son Co. Archived from the original on April 13, 2003 via North Carolina State University: Mountain Horticultural Crops Research and Extension Center. Triploid. May be a hybrid between tetraploid U. americana and an unknown diploid species.
  4. Pooler, Margaret R.; Townsend, A. M. (September 2005). "Research Reports: DNA Fingerprinting of Clones and Hybrids of American Elm and Other Elm Species with AFLP Markers" (PDF). Journal of Environmental Horticulture. Washington, D.C.: Horticultural Research Institute (HRI), the AmericanHort Foundation. 23 (3): 113–117. doi: 10.24266/0738-2898-23.3.113 . ISSN   0738-2898. LCCN   83643944. OCLC   1057932522. Archived from the original (PDF) on May 8, 2018. Retrieved January 30, 2021 via elmpost.org elmpost.org]. (Jefferson's) identity has been questioned due to its disease tolerance, broad U-shaped branch unions, and bark, branch, and leaf characteristics..
  5. (1) Kaplan, Kim (March 30, 2011). "Hidden elm population may hold genes to combat Dutch elm disease". Research News. United States Department of Agriculture: Agricultural Research Service. Archived from the original on April 6, 2019. Retrieved January 30, 2021. To settle the question, the two scientists tested elm trees from across the species' eastern and central U.S. range. About 21 percent of the wild elms sampled were diploid; some grew in stands with tetraploids, while others were larger groupings of diploids..
    (2) Whittemore, Alan T.; Olsen, Richard T. (April 1, 2011). "Ulmus americana (Ulmaceae) is a polyploid complex". American Journal of Botany . St. Louis: Botanical Society of America. 98 (4): 754–760. doi:10.3732/ajb.1000372. ISSN   0002-9122. JSTOR   41149435. LCCN   17005518. OCLC   937099651. PMID   21613171 . Retrieved January 30, 2021. The two ploidy levels grew in proximity to one another at several sites, east of the Appalachians and in eastern Missouri and west-central Oklahoma. Despite finding diploid and tetraploid trees growing near each other in several areas, no wild triploids were encountered.
  6. Townsend, A. M.; Bentz, S. E.; Douglass, L. W. (March 2005). "Evaluation of 19 American Elm Clones for Tolerance to Dutch Elm Disease" (PDF). Journal of Environmental Horticulture. Washington, D.C.: Horticultural Research Institute (HRI), the AmericanHort Foundation. 23 (1): 21–24. doi: 10.24266/0738-2898-23.1.21 . ISSN   0738-2898. LCCN   83643944. OCLC   1057932522. Archived from the original (PDF) on May 11, 2005. Retrieved September 7, 2010 via elmpost.org elmpost.org]..
  7. "Elm Leaf Beetle Survey". Clinton, Oklahoma: Sunshine Nursery & Arboretum. Archived from the original on July 19, 2011. Retrieved July 17, 2017.
  8. (1) Sinclair, W. A.; Townsend, A..M.; Sherald, J. L. (May 2001). Karasev, Alexander V. (ed.). "Elm Yellows Phytoplasma Lethal to Dutch Elm Disease-Resistant Ulmus americana Cultivars". Plant Disease . St. Paul, Minnesota: American Phytopathological Society. 85 (5): 560. doi:10.1094/PDIS.2001.85.5.560B. ISSN   0191-2917. LCCN   79643690. OCLC   819181727. PMID   30823144. Archived from the original on February 1, 2021. Retrieved February 1, 2021..
    (2) "Elm yellows (Candidatus Phytoplasma ulmi)". Forest Research. England: Forestry Commission. 2020. Archived from the original on December 2, 2020. Retrieved February 1, 2021. Infection can be very destructive to some elms, particularly North American species. However, it is thought that European elm species tend to be much less affected than the highly susceptible American elm (U. americana)..
  9. Miller, Fredric; Ware, George; Jackson, Jennifer (April 1, 2001). "Preference of Temperate Chinese Elms (Ulmus spp.) for the Adult Japanese Beetle (Coleoptera: Scarabaeidae)". Journal of Economic Entomology. Oxford University Press (OUP). 94 (2): 445–448. doi: 10.1603/0022-0493-94.2.445 . ISSN   0022-0493. LCCN   11008063. OCLC   1131914636. PMID   11332837. S2CID   7520439.
  10. Pegg, G. F.; Brady, B. L. (2002). Verticillium Wilts. Wallingford, Oxon, UK: CABI Publishing. p.  291. ISBN   0-85199-529-2. LCCN   2001037313. OCLC   290478616 via Google Books.
  11. 1 2 Zetterstrom, Tom (2017). Pinchot, Cornelia C.; Knight, Kathleen S.; Haugen, Linda M.; Flower, Charles E.; Slavicek, James M. (eds.). "Report From the Street" (PDF). Proceedings of the American Elm Restoration Workshop 2016; 2016 October 25–27; Lewis Center, OH. Newtown Square, PA. United States Department of Agriculture, United States Forest Service, Northern Research Station: 119–121. doi: 10.2737/NRS-GTR-P-174 . OCLC   1231892730. Gen. Tech. Rep. NRS-P-174. Archived from the original (PDF) on May 1, 2019. Retrieved February 7, 2021. Consumers need to also be aware that a nursery trade mix-up a dozen years ago still plays out in the marketplace, and 'Princeton' elms continue to be sold as 'Jefferson' unknowingly by reputable nurseries from New York to Minnesota. .... National Elm Trial (NET) results were inconclusive and provided no data on 'Jefferson' due to the cultivar mix-up..
  12. Griffin, Jason J.; Jacobi, E., William R.; McPherson, Gregory; Sadof, Clifford S.; et al. (2017). "Ten-Year Performance of the United States National Elm Trial" (PDF). Arboriculture & Urban Forestry. International Society of Arboriculture. 43 (3): 107–120. doi:10.17660/ActaHortic.2018.1191.5. ISSN   0567-7572. OCLC   7347020445 . Retrieved February 7, 2021.
  13. "Jefferson American Elm vs. Princeton American Elm". Disease-Resistant Elm Identification Guide. University of Minnesota: Urban Forestry Outreach, Research & Extension: The UFore Nursery & Lab. Archived from the original on February 7, 2021. Retrieved February 7, 2021..

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

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

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References