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The American elm is a deciduous tree which, under ideal conditions, can grow to heights of 21 to 35 meters (69 to 115 feet). [3] The trunk may have a diameter at breast height (dbh) of more than 1.2 m (4 ft), supporting a high, spreading umbrella-like canopy.
The tree can grow to greater than 30 m in height, and is distinguished by its dense, symmetrical, upright form and dark green foliage, ultimately forming a broad umbrella crown. Crotch angles can be acute, with considerable bark inclusion which can later lead to branch breakages.
The American elm cultivar Ulmus americana 'New Harmony' was raised by the Maryland Agricultural Research Service and released by the United States National Arboretum in 1995, along with 'Valley Forge'. 'New Harmony' proved the most successful U. americana cultivar in the US National Elm Trial, averaging a survival rate of 85.5% overall. [1]
Ulmus americana var. floridana, the Florida elm, first described as Ulmus floridana by Alvan Wentworth Chapman in the 1860s, is smaller than the type, and occurs naturally in north and central Florida south to Lake Okeechobee.
The tree is highly resistant to Dutch elm disease. [1] No other specific information is available, but the species as a whole is highly susceptible to Elm Yellows; it is also moderately preferred for feeding and reproduction by the adult Elm Leaf Beetle Xanthogaleruca luteola, [3] and highly preferred for feeding by the Japanese Beetle Popillia japonica [4] [5] in the United States.
The American elm cultivar Ulmus americana 'Aurea' was cloned from a tree discovered by F. L. Temple in Vermont at the end of the 19th century. [1] [2] Description
The Ulmaceae (/ ʌ l ˈ m eɪ s i /) are a family of flowering plants that includes the elms (genus Ulmus), and the zelkovas (genus Zelkova). [3] Members of the family are widely distributed throughout the north temperate zone, and have a scattered distribution elsewhere except for Australasia.
Ulmus americana L. var. glabra Planch. Accepted Name: Ulmus americana L. Ulmus americana L. var. pendula Aiton . Accepted Name: Ulmus americana L. Ulmus americana L. var. scabra Spach . Accepted Name: Ulmus americana L. Ulmus americana L. var. foliis variegatis Hort. Loudon. Accepted Name: Ulmus americana 'Folia Aurea Variegata' Ulmus americana ...