The Morton Arboretum, at Lisle, Illinois, is home to the largest Elm collection in North America
(www.cirrusimage.com has detailed studies of nearly 20 of these species,
as well as numerous hackberries and zelkovas). 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. The 12 species being studied are: the Bergmann (Ulmus bergmanniana), 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 Father 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. [2]
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Hobei Elm, Morton Arboretum accession 317-90*1 is 30 years old. [1] |
A slow growing tree to 10 m, U. lamellosa is
single or multi-stemmed, its upright branches forming a rounded crown.
The leaves, on 3 mm - 8 mm petioles, are obovate, < 10 cm long by 5.5 cm
wide, caudate at the apex, with simply to doubly serrate margins, and
densely pubescent when young.
Rare in cultivation beyond China, it is one of a number of Chinese
species which were assessed for their horticultural merit at the Morton
Arboretum where it was adjudged suitable for planting in parks and
gardens, but typically intolerant of wet soils. Although known to
propagate satisfactorily, U. lamellosa is only very rarely found in
commerce in Europe and the USA; there are no known cultivars.
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The Ulmus glabra – Ulmus minor clade—A clade
comprising Ulmus glabra, U. procera [= U. minor], U. × hollandica
(U. glabra × U. minor), and one of our (Morton
Arboretum) U. pumila accessions is strongly supported (bootstrap
= 0.97). This clade falls sister to a clade comprising U. foliacea,
U. sukaczevii [= U. glabra], U. elliptica [= U. glabra], U.
wallichiana (perhaps sister to U. elliptica, though this bears
investigation with additional material). U. pumila, U.
microcarpa, U. glaucescens var. lasiocarpa, U. lamellosa. Within
this latter clade, Ulmus glaucescens var. lasiocarpa and U.
lamellosa come out sister to one another, which is
supported by a very distinctive bark character. [5] |
American Elm in glorious yellow autumn colors,
Morton Arboretum acc. 170-U*4, age unknown.
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When I was a child in the 1950's, Thacker Street in Des Plaines, Illinois, was lined with huge Elm trees. We walked to school shaded by those magnificent trees; they were so tall, their branches overarched the street completely. It was a wonderful walk then, and especially in fall when our mornings were bathed in yellow light filtering through the glorious butter yellow foliage. Of course, we gathered leaves to take into school with us, to trace and do rubbings with fat Crayons from our (newly introduced) 64 packs. But when the school year started in 1960, those trees had all been cut down, victims of Dutch Elm Disease. It was so sad, and now we walked under blazing sun and boy, did we miss those trees. Similar scenarios are now playing themselves out amongst the lodgepole pine and ash trees of North America. |
Family Ulmaceae Main Page Graphics
| Tree Encyclopedia Main Page Graphics
| Trees Table of Contents
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Ulmaceae Table of Contents | |
References-
Hobei Elm, Morton Arboretum accession 317-90*1, photographed October 25, 2010 by Bruce Marlin
- The Morton Arboretum, Arboretum Records Honor, Milestone; Looks to Future, http://www.mortonarb.org/res/GEORGEWARE.pdf
- USDA, NRCS Plants Profile, "Rock Elm, Ulmus thomasii Sarg."
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Andrew L. Hipp, Linus Gog, Jaime A. Weber, and Alicia B.
Giesler, "Evaluating
the taxonomy of elms (Ulmus) using DNA sequence data"
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