Rock Elm – Ulmus thomasii

Rock Elm – Ulmus thomasii

Rock Elm fall foliageA medium-sized to large tree that grows best on moist loamy soils in southern Ontario, lower Michigan, and Wisconsin, it may also be found on dry uplands, especially rocky ridges and limestone bluffs.

Rock ElmFamily Ulmaceae – Hackberry, Elm
Rock elm is most common in the Upper Mississippi Valley and lower Great Lakes basin.

Rock Elm in fall colorsThe rock elm pictured above  (both summer and autumn) is 25 years old

Rock elm is also called cork elm because of the irregular thick corky wings on older branches.

Rock Elm summer foliage

On good sites, rock elm may reach 30 m (100 ft) in height and 300 years of age. It is always associated with other hardwoods and is a valued lumber tree.

The extremely hard, tough wood is used in general construction and as a veneer base. Rock Elm Bark


  1. Rock Elm – Ulmus thomasii Morton Arboretum acc. 178-84-1photos © Bruce Marlin
  2. The Morton Arboretum, Arboretum Records Honor, Milestone; Looks to Future
  3. Ohio State University, Ohio Trees, Bulletin 700-00 “Ulmus – Elm” Key to Ulmus Species

Family Ulmaceae – Zelkovas, Hackberries and Elms
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Tree Encyclopedia / North American Insects & Spiders

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