Bergmann's Elm - Ulmus bergmanniana
Family Ulmaceae - Zelkova, Hackberry, Elm

This species has been assessed by the Morton Arboretum and is the most cold-hardy of the elms.
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Bergmann's Elm foliage
Bergmann's Elm is native to China, generally found growing between 1500-2600 meters in Anhui, Gansu, Henan, Hubei, Hunan, Jiangxi, Shaanxi, Shanxi, Sichuan, Yunnan, and Zhejiang provinces. [1]

This tree is very closely related to the Wych Elm Ulmus glabra; it can reach a height of 26 m with a wide-spreading crown. The bark is longitudinally fissured, and varies in colour from greyish-white to dark grey. The leaves range from obovate to elliptic, less than 16 cm long, and bluish-green in color. The perfect, wind-pollinated apetalous flowers are produced on second-year shoots in February, followed by generally orbicular samarae less than 16 mm in diameter. Branchlets do not possess the corky wings characteristic of many other elm species.

Bergmann's elm is somewhat resistant to Duth Elm Disease, and in the Morton Arboretum's assessment, it is a suitable replacement for the American elm in shade or street tree plantings [1].

Bergmann's Elm
Ulmus bergmanniana, obtained as a plant from Yunan, China, is 13 years old.
The Morton Arboretum, at Lisle, Illinois, is home to the largest Elm collection in North America. Under study, the collection includes almost all of the 22 Elm species native to China, a dozen of which show resistance to Dutch elm disease and elm yellows. The Arboretum in past years has bred and marketed five new elm varieties resistant to Dutch elm disease.
Bergmann's Elm bark
The 12 species being studied are: the Bergmann (featured here), Taihang Mountain (U. taihangshanensis), Tibetan (U. microcarpa), Anhui (U. gaussenii), Hebei (U. lamellosa), Harbin (U. harbinensis), corkbark (U. propinqua var. suberosa), plum-leaved (U. prunifolia), Chenmou (Ulmus chenmoui), Gansu (Ulmus glaucescens var. lasiocarpa), chestnut-leaved (U. castaneifolia) and David (U. davidiana var. mandshurica) elms.

These 12 Chinese trees are virtually unknown in the U.S., but are under close study at the arboretum. Dendrologist Emeritus and former research director Dr. George Ware, and Arboretum Assistant Director of Collections Kunso Kim are responsible for their observation and data collection. Their efforts may help ameliorate the effects of numerous maladies affecting trees around the world, such as Emerald Ash Borer, Oak wilt, Asian Longhorned Beetle, Pine Sawyer Beetle, et al.

"These and other problems underscore the urgent need for the Arboretum and others to continue seeking new species for urban use," Kim says. The average lifespan of an urban tree is fewer than 10 years, according to Ware. But "planting hardier trees increases the likelihood of a longer life span and a greener world - a goal that has never been more important than now, with climate change upon us."[3]

References
  1. Flora of China, Ulmus bergmanniana
  2. NATIONAL AUDUBON SOCIETY, Field Guide to North American Trees--E: Eastern Region
  3. The Morton Arboretum, Arboretum Records Honor, Milestone; Looks to Future
Tree Encyclopedia / North American Insects & Spiders is dedicated to providing scientific and educational resources for our users through use of large images and macro photographs of flora and fauna.
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Family Ulmaceae - Zelkovas, Hackberries and Elms
There are about 200 species of trees and shrubs in Ulmaceae. Elms fell victim to Dutch Elm disease during the 1950s; until that time, they were the premier shade tree along the streets of our American towns and cities. The Morton Arboretum in past years has bred and marketed five new elm varieties resistant to Dutch elm disease.
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