Jefferson (elm cultivar)

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The American Elm U. americana cultivar Jefferson is a tree of unknown origin. Dutch elm disease tolerant, it is unusual among elms in having triploid chromosome levels, suggesting it may be a hybrid between the tetraploid American Elm and a diploid species. Jefferson, introduced by the U. S. National Parks Service, has a vase-shaped habit, with arching limbs to a height of about 12 m and a spread of similar dimension.

Neither Jefferson nor its triploid sibling Washington have been widely tested beyond Washington D.C., and are not known to have been introduced to Europe or Australasia.

[edit] External links

• 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.