'Penn Treaty' is a cultivar of 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, discovered in the Plant Sciences Data Center of the American Horticultural Society

American Horticultural Society

The American Horticultural Society is a nonprofit, membership-based organization that promotes excellence in American horticulture. It is headquartered in Alexandria, Virginia....

. Plants under that name were raised at the Morris Arboretum

Morris Arboretum

The Morris Arboretum of the University of Pennsylvania is the official arboretum of the Commonwealth of Pennsylvania. It is located at 100 East Northwestern Avenue, Chestnut Hill, Philadelphia, Pennsylvania...

, Pennsylvania

Pennsylvania

The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...

, Philadelphia, from grafts made in 1945 from a tree at Haverford College

Haverford College

Haverford College is a private, coeducational liberal arts college located in Haverford, Pennsylvania, United States, a suburb of Philadelphia...

, itself a graft from the Shackamaxon

Shackamaxon

Shackamaxon or Shakamaxon was a historic village along the Delaware River inhabited by Delaware Indians in North America. It was located within what are now the borders of the city of Philadelphia, Pennsylvania, United States....

 Treaty Elm (felled by a storm in 1810) in what was later named Penn Treaty Park

Penn Treaty Park

Penn Treaty Park is a small park on the western bank of the Delaware river, in the Fishtown neighborhood of Philadelphia, Pennsylvania. It is located at the intersection of Delaware Avenue and Beach Street, just off Delaware Avenue.- Overview :...

, Kensington, Pa..

Description

The elm at Haverford, planted in 1840, measured 90 ft (28 m) in height, with a crown diameter of 120 ft (37 m) 100 years later.

Pests and diseases

The Haverford elm http://www.haverford.edu/Arboretum/october06.htm was felled in 1977 after it had succumbed 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...

.

Cultivation

Cuttings were taken in 1915, although all but one of the resultant trees have also died, the survivor still thrives (2006) at Barclay Beach. Moreover, a specimen raised from seed survives on Founder's Green, Haverford College, and is perpetuated by selfed seedlings assiduously gathered by the arboretum staff in autumn. The tree is not known to be in cultivation beyond North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

, nor is it in commerce.