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Ulmus thomasii From Wikipedia, the free encyclopedia
This article is about the tree. For the town in Wisconsin, see Rock Elm, Wisconsin. Ulmus thomasii Sarg., the Rock Elm or Cork Elm, is a deciduous tree native primarily to the Midwestern United States. The tree Ulmus thomasii
ranges from southern Ontario and Quebec, south to Tennessee, west to northeastern Kansas, and north to Minnesota. [1] Its preferred habitat is moist but well­drained sandy loam, loam, or silt loam soil, mixed with other hardwoods; it is moderately shade­tolerant.[2] However, it also grows on dry uplands, especially on rocky ridges and limestone bluffs. Contents[hide] 1 Description 2 Pests and diseases 3 Cultivation and uses 4 Hybrids and hybrid cultivars 5 Etymology 6 Accessions 7 References Description [edit]
Rock Elm, Meise.
The tree grows from 15–30 m tall and may live up to 300 years. Where forest­grown, the crown is cylindrical and upright with short branches, and is narrower than most other elms. Rock Elm is also unusual among elms in that it is often monopodial. [3] The bark is grey­brown and deeply furrowed into scaly, flattened ridges. Many older branches have 3­4 irregular thick corky wings. It is for this reason the Rock Elm is sometimes called the Cork Elm.[4] The leaves are 5 – 10 cm long and 2 – 5 cm wide, oval to obovate with a round, symmetrical base and acuminate apex. The leaf surface is shiny dark green, turning bright yellow in autumn; the underside is pubescent. The perfect apetalous, wind pollinated flowers are red­green and appear in racemes < 40 mm long two weeks before the leaves from March to May, depending on the tree's location. The fruit is a broad ovate samara 13 – 25 mm long covered with fine hair, notched at the tip, and maturing during May or June to form drooping clusters at the leaf bases.[5] Although U. thomasii is protandrous, levels of self­pollination remain high.[6]
Scientific classification
Kingdom:
Plantae
Division:
Magnoliophyta
Class:
Magnoliopsida
Order:
Rosales
Family:
Ulmaceae
Genus:
Ulmus
Species:
U. thomasii
Binomial name
Ulmus thomasii Sarg.
Synonyms
Cork Elm. Anon. Ulmus racemosa (not Borkh.) Thomas Pests and diseases [edit]
Like most North American elms, the Rock Elm is very susceptible to Dutch elm disease. Cultivation and uses [edit]
The wood is the hardest and heaviest of all elms, and where forest grown remains comparatively free of knots and other defects. It is also very strong and takes a high polish, consequently it was once in great demand in America and Europe for a wide range of uses, notably shipbuilding, furniture, agricultural tools, and musical instruments. Much of the timber's strength is derived from the tight grain arising from the tree's very slow rate of growth, the trunk typically increasing in diameter by < 2 mm a year. Over 250 annual growths were once counted in a log 24 cm square being sawn for gunwales in an English boatyard, while a tree once grown at Kew Gardens, London, attained a height of only 12 m in 50 years.[7] Wholly unsuited to the more temperate, maritime climate of northern Europe, the Rock Elm is extremely rare in cultivation across the Atlantic, although there have been unconfirmed reports of others in south­west Essex, England. There are no known cultivars of this taxon, nor is it known to be in commerce. Hybrids and hybrid cultivars [edit]
The species was crossed with Japanese Elm at the Arnold Arboretum, but no clones were ever released to commerce.[6] Seedlings arising from crossings with Siberian Elm U. pumila at the Lake States Forestry Experimental Station in the 1950s all perished, a classic case of hybrid lethality [3] . [8] Etymology [edit]
The tree was named in 1902 for David Thomas, an American civil engineer, who first identified the tree (as Ulmus racemosa) in the early 19th century. Accessions [edit]
North America Arnold Arboretum. Acc. no. 444­88. Brenton Arboretum, Dallas Center, Iowa. No acc. details available. Dominion Arboretum, Ottawa, Canada. No acc. details. Morton Arboretum. Acc. no. 178­84, wild collected from Reedsville, Wisconsin, 843­2005 (Kelleys Island, Sandusky, Erie County), 122­2006 (Dixon County, Nebraska). Nebraska Statewide Arboretum. No details available. Europe Grange Farm Arboretum, Sutton St. James, Spalding, Lincs. UK. Acc. no. 706. National Botanic Gardens, Ireland, [9] Glasnevin, Dublin, Ireland. Location: A3 (155) National Botanic Garden of Belgium, [10] Meise, Belgium. Acc. no. 19800105. Wakehurst Place Garden Wakehurst Place, UK. Acc. no. 1968­48603. References [edit]
1.
^ "Ulmus Thomasii Range Map"
2.
3.
^ http://forestry.about.com/library/silvics/blsilulmtho.htm ^ Bean, W. J. (1981). Trees and shrubs hardy in Great Britain, 7th edition. Murray, London. 4.
5.
^ Photograph of corky ridges of Rock Elm branches, Michigan State University Plant Encyclopedia [1]
^ White, J & More, D. (2003). Trees of Britain & Northern Europe. Cassell's, London. 6.
7.
8.
9.
10.
. United States Geological Survey. Retrieved 2008­03­02. ^ a b Hans, A. S. (1981). Compatibility and Crossability Studies in Ulmus. Silvae Genetica 30, 4 ­ 5 (1981). ^ Elwes, H. J. & Henry, A. (1913). The Trees of Great Britain & Ireland. Vol. VII. pp 1848­1929. Private publication. [2] ^ Sholtz, H. F. (1957). Rock Elm (Ulmus thomasii). Lake States Forest Experimental Station Paper 47:16. ^ http://www.botanicgardens.ie ^ http://translate.google.co.uk/translate?hl=en&sl=nl&u=http://nl.wikipedia.org/wiki/Nationale_Plantentuin_van_Belgi%25C3%
25AB&ei=hiUtSqXdOYmQjAefoJjzCg&sa=X&oi=translate&resnum=4&ct=result&prev=/search%3Fq%3DBotanische%2BTuin%2BMeisse%2Bwiki%26hl%3Den%26sa%3DG
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