Jefferson (elm cultivar)

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Ulmus americana
Cultivar
Jefferson
Origin
National Parks Service, USA

The American Elm U. americana cultivar Jefferson is a Dutch elm disease tolerant tree of unknown origin. Although early reports of studies on this clone had indicated that it had triploid chromosome levels (suggesting it may be a hybrid between the tetraploid American Elm and a diploid species), a genetic study performed by the United States National Arboretum in 2004 [1] appears to call this supposition strongly into question, suggesting that the cultivar is in fact tetraploid, as is typical of the American elm as a species. The Jefferson elm, introduced by the U. S. National Parks Service in 2004, has a low, spreading form with arching limbs to a height of about 12 m. Neither Jefferson nor the cultivar Washington has been widely tested beyond Washington D.C..

Contents 1 Arboreta etc. accessions 1.1 North America 2 Nurseries 2.1 North America 3 External links

[edit] Arboreta etc. accessions

[edit] North America

• Bartlett Tree Experts [2], acc. nos. 2001-255/6/7.
• Longwood Gardens, acc. no. 2002-0413.

[edit] Nurseries

[edit] North America

• Sunshine Nursery [3], Oklahoma.

[edit] External links

• DNA Fingerprinting of Clones and Hybrids of American Elm and Other Elm Species with AFLP Markers. Summary of a genetic study which suggests strongly that the Jefferson elm is tetraploid.
• http://www.elmpost.org/2005-02.htm Photograph showing the mature form of the Jefferson elm.
• http://www.sunshinenursery.com/elms.htm Review of current elm selections in the USA.
• http://fletcher.ces.state.nc.us/programs/nursery/metria/metria11/warren/elm.htm Return of the Elm -the status of elms in the nursery industry in 2000. Warren, K., J. Frank Schmidt and Co.