Seems the USDA Research team is finding out more information on the genetics on the American Elm. From the research we have learned that American Elms come with different numbers of chromosome's. Some are tetraploids (4) sets, triploids (3) sets and diploids (2) sets of chromosome. It is inside these set of chromosome that give certain American Elms thier resistance to the DED (Dutch Elm Disease).
What was not known was what stands of the American Elms in the wild are. Alan Whittemore and Richard Olsen, both with the USDA have tested native blocks of the American Elm and have found many to be diploid's. This was interesting because to get a triploid, you needed a tetraploid and diploid as parents.
There is too much information and detailed to go into here, but you could go to the ARS (Agricultural Research Serivce web site and read more. This story is developing further this summer as both scientist continue to look into the diploid genetic American Elm. Very Exciting.
