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Ulmus thomasii
Also called Cork elm
Rock elm (Ulmus thomasii) is a slow-growing, deciduous forest tree from eastern North America, grown mainly as a specimen or street tree in its native range. It is rarely cultivated and not commonly sold, so care notes are general.
Ulmus thomasii, the rock elm or cork elm (or orme liège in Québec), is a deciduous tree native primarily to the Midwestern United States. The tree ranges from southern Ontario and Quebec, south to Tennessee, west to northeastern Kansas, and north to Minnesota.
There are no known cultivars of Ulmus thomasii, nor is it known to be any longer in commerce. It appeared in some US nursery catalogues in the early 20th century. It has, however, been planted as a street tree in Cheyenne, Wyoming, where in tight lines it keeps a monopodial habit recalling Jersey elm. The species is occasionally grown beyond its native range as a specimen tree in botanical gardens and arboreta, for example in northwestern Europe, but not commonly cultivated in northern Europe, being unsuited to the region's more temperate, maritime climate. However, the tree was propagated and marketed in the UK by the Hillier & Sons nursery, Winchester, Hampshire, from 1965 to 1977, during which time 49 were sold.
Ulmus thomasii was crossed experimentally with Japanese elm (U. davidiana var. japonica) at the Arnold Arboretum in Massachusetts, but no clones were released to commerce. 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.
Ulmus thomasii is moderately shade-tolerant. Its preferred habitat is moist but well-drained sandy loam, loam, or silt loam soil, mixed with other hardwoods. However, it also grows on dry uplands, especially on rocky ridges and limestone bluffs.
The wood of the rock elm 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, and consequently was once in great demand in America and Europe for a wide range of uses, notably boatbuilding, furniture, agricultural tools, and musical instruments.
Winged elm · American elm · Ulmus 'Androssowii' · Cedar elm · Wych Elm · European White Elm · Ulmus lanceifolia · Ulmus minor 'Plotii' · Chinese elm · Siberian elm · Slippery elm · Elm
Text excerpted from the Wikipedia article Ulmus thomasii by its contributors, under CC BY-SA 4.0; the excerpts and the care summary drawn from them are shared under the same licence.
The care summary was written by AI (Claude, Anthropic) from the sources on this page, with general growing knowledge where they are silent. Check before relying on it.
Life form, climate and native range: World Checklist of Vascular Plants, Royal Botanic Gardens, Kew (CC BY 3.0), reformatted; see Plants of the World Online.
