Ulmus americana 'American Liberty'
Encyclopedia
The American Elm
American Elm
Ulmus americana, generally known as the American Elm or, less commonly, as the White Elm or Water Elm, is a species native to eastern North America, occurring from Nova Scotia west to Alberta and Montana, and south to Florida and central Texas. The American elm is an extremely hardy tree that can...

 Ulmus americana cultivar 'American Liberty' is in fact a group of six genetically distinct cultivars under a single name, although they are superficially similar . The Liberty elm is reportedly suitable for street planting, being tolerant of de-icing salts and air pollution. However, examples included in 10-year trials at Atherton
Atherton, California
Atherton is an incorporated town in San Mateo County, California, United States. Its population was 6,914 at the 2010 census. In September 2010, Forbes magazine placed Atherton's zip code of 94027 at #2 on its annual list of America's most expensive zip codes, with a median home price of $4,010,200...

, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

 to evaluate replacements for Californian elms lost to disease did not perform well. The late Professor Eugene Smalley
Eugene Byron Smalley
Professor Eugene Byron Smalley was an American plant pathologist. Smalley joined the University of Wisconsin-Madison in 1957 with the specific aim of finding a way to control Dutch elm disease Assembling seeds from around the northern hemisphere, Smalley developed resistant strains of elms which...

 summarized 'American Liberty' as "not as resistant as the Asian hybrids, but it still has the look of a classic American Elm" http://query.nytimes.com/gst/fullpage.html?res=950DE5DC163AF936A35751C1A96F948260&sec=health&spon=&pagewanted=all

Pests and diseases

The six clones which comprise this series vary considerably in their level of resistance to Dutch elm disease
Dutch elm disease
Dutch elm disease is a disease caused by a member of the sac fungi category, affecting elm trees which is spread by the elm bark beetle. Although believed to be originally native to Asia, the disease has been accidentally introduced into America and Europe, where it has devastated native...

, and none is immune, but some evidence suggests that at least one of the six clones may have a fairly high degree of DED-resistance http://www.elmpost.org/liberty.htm. It is claimed, controversially, by ERI that fewer than 180 American Liberty elm trees have been known to succumb to DED since the planting began in the early 1980's. This figure is surprising in the light of Townsend & Douglass's work , which found that the Liberty elms exhibited only an 18% survival rate four years after inoculation, compared with 96% for both 'Valley Forge'
Ulmus americana 'Valley Forge'
The American Elm Ulmus americana cultivar Valley Forge was raised by the Agricultural Research Service in Maryland and released to wholesale nurseries without patent restrictions by the U. S. National Arboretum in 1995.-Description:...

 and 'Princeton'
Ulmus americana 'Princeton'
The American Elm Ulmus americana cultivar Princeton was originally selected in 1922 by New Jersey nurseryman William Flemer for its aesthetic merit...

, and 100% for the Japanese Elm clone 'Prospector'
Ulmus davidiana var. japonica 'Prospector'
Prospector was originally treated as a cultivar of Wilson's Elm U. wilsoniana Schneid., a species sunk as Ulmus davidiana var.japonica by Fu . A U.S...

.

The 'American Liberty' elms also sustained wind damage in winter, and high levels of injury from the elm leaf beetle Xanthogaleruca luteola
Xanthogaleruca luteola
Xanthogaleruca luteola, commonly known as the Elm Leaf Beetle, is a serious pest of the elm. Indigenous to Europe, it was accidentally introduced to North America. Both the imagines and larvae feed on the emergent leaves of the elm...

. Accordingly, the cultivar was deemed "highly questionable as a replacement" .
Moreover, the trees were noted as highly susceptible to Elm Yellows
Elm Yellows
Elm Yellows is a plant disease of elm trees that is spread by leafhoppers or by root grafts. Elm Yellows, also known as Elm Phloem Necrosis, is very aggressive, with no known cure. Elm Yellows occurs in the Eastern United States and southern Ontario in Canada. It is caused by phytoplasmas which...

 in New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...

 . Examples tested by research scientists at the United States National Arboretum
United States National Arboretum
The United States National Arboretum is an arboretum in Washington, D.C., operated by the United States Department of Agriculture's Agricultural Research Service as a division of the Henry A. Wallace Beltsville Agricultural Research Center...

 in the 1992-1993 also failed to perform well http://www.elmpost.org/report1.htm; but unfortunately, it has never been clear which of the six clones were represented in the tests, so the results remain largely inconclusive.

Cultivation

Promoted exclusively by the Elm Research Institute (ERI) http://www.elmresearch.org/ since 1983, these trees have been planted across the United States in numbers the organization claims to be in excess of 250,000. The American Liberty elm is reputedly "extremely expensive" to buy, particularly in the larger sizes .
The tree is not known to have been introduced to Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

 or Australasia
Australasia
Australasia is a region of Oceania comprising Australia, New Zealand, the island of New Guinea, and neighbouring islands in the Pacific Ocean. The term was coined by Charles de Brosses in Histoire des navigations aux terres australes...

.
North America
  • Brooklyn Botanic Garden
    Brooklyn Botanic Garden
    Brooklyn Botanic Garden is a botanical garden in the borough of Brooklyn in New York City. Located near the Prospect Heights, Crown Heights, and Park Slope neighborhoods, the garden includes a number of specialty "gardens within the Garden," plant collections, and the Steinhardt Conservatory,...

     http://www.bbg.org/cgi/bgbase/search.cgi, New York
    New York
    New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...

    . Acc. no. 890269.
  • Dawes Arboretum
    Dawes Arboretum
    The Dawes Arboretum is a non-profit arboretum located outside of Columbus in Newark, Ohio. As one of the premier public gardens in North America, The Dawes Arboretum has over of plant collections, gardens and natural areas...

     http://www.dawesarb.org/collectionsgardens/plant-search.asp, Newark
    Newark, Ohio
    In addition, the remains of a road leading south from the Octagon have been documented and explored. It was first surveyed in the 19th century, when its walls were more apparent. Called the Great Hopewell Road, it may extend to the Hopewell complex at Chillicothe, Ohio...

    , Ohio
    Ohio
    Ohio is a Midwestern state in the United States. The 34th largest state by area in the U.S.,it is the 7th‑most populous with over 11.5 million residents, containing several major American cities and seven metropolitan areas with populations of 500,000 or more.The state's capital is Columbus...

    . 2 trees, no acc. details available.
  • Dominion Arboretum
    Dominion Arboretum
    The Dominion Arboretum is located at the Central Experimental Farm of Agriculture and Agri-Food Canada in Ottawa, Ontario, Canada.Originally begun in 1889 the Arboretum covers about 26 ha of rolling land between Prince of Wales Drive, Dow's Lake and the Rideau Canal. Carleton University is located...

     http://www.agr.gc.ca/sci/arboretum/index_e.php?section=specimens&page=141ulm&PHPSESSID=28c7cb5641bcf4dd8e6dd948ebd359bb, Canada
    Canada
    Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

    . No details available.
  • Holden Arboretum
    Holden Arboretum
    The Holden Arboretum, in Kirtland, Ohio, USA, is one of the largest arboretums and botanical gardens in the United States, with over 3,500 acres , 600 acres of which are devoted to collections and gardens. Diverse natural areas and ecologically sensitive habitats make up the rest of the holdings...

    . Two trees > 13 m in height (2006). Acc. no. 84-336.
  • Scott Arboretum
    Scott Arboretum
    Scott Arboretum is an arboretum located across the campus of Swarthmore College, 500 College Avenue, Swarthmore, Pennsylvania. It is open to the public daily without charge....

    . Acc. no. 84-276.

External links

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