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Ulmus thomasii (Rock elm)
Makin, Julie

Ulmus thomasii

Ulmus thomasii Sarg.

Rock Elm, Cork Elm

Ulmaceae (Elm Family)

Synonym(s): Ulmus racemosa


USDA Native Status: L48 (N), CAN (N)

Tree with usually straight trunk and narrow, cylindrical crown of short, drooping branches.

The valuable wood is hard, tough, and difficult to split, making it particularly suitable for agricultural implements and tool handles. In the 19th century, this durable timber was exported to England for construction of wooden battleships and sailing vessels.


From the Image Gallery

37 photo(s) available in the Image Gallery

Plant Characteristics

Duration: Perennial
Habit: Tree
Leaf Retention: Deciduous
Leaf Arrangement: Alternate
Leaf Complexity: Simple
Leaf Shape: Oblong , Obovate , Oval
Leaf Venation: Pinnate
Leaf Margin: Double-serrate
Leaf Apex: Acuminate
Leaf Base: Oblique
Inflorescence: Cyme
Fruit Type: Samara
Size Notes: Up to about 100 feet tall.
Leaf: Green
Autumn Foliage: yes
Fruit: Green

Bloom Information

Bloom Color: Yellow , Green , Brown
Bloom Time: Mar , Apr


USA: AR , CT , IA , IL , IN , KS , KY , MA , MD , MI , MN , MO , ND , NE , NJ , NY , OH , PA , SD , TN , VT , WI , WV
Canada: ON , QC
Native Distribution: S. Ontario, extreme S. Quebec, and W. New England south to Tennessee, west to extreme NE. Kansas, and north to Minnesota; at 200-2500' (61-762 m).
Native Habitat: Moist to dry uplands, especially rocky ridges and limestone bluffs, also flatlands; in hardwood forests.

Growing Conditions

Water Use: High
Light Requirement: Sun , Part Shade , Shade
Soil Moisture: Dry , Moist
Soil pH: Alkaline (pH>7.2)
CaCO3 Tolerance: High
Soil Description: Clay


Use Wildlife: Birds, Other Showy Insects
Attracts: Birds , Butterflies
Larval Host: Mourning Cloak, Columbia silkmoth

Butterflies and Moths of North America (BAMONA)

Mourning Cloak
(Nymphalis antiopa)

Larval Host
Learn more at BAMONA
Columbia silkmoth
(Hyalophora columbia)

Larval Host
Learn more at BAMONA

National Wetland Indicator Status

This information is derived from the U.S. Army Corps of Engineers National Wetland Plant List, Version 3.1 (Lichvar, R.W. 2013. The National Wetland Plant List: 2013 wetland ratings. Phytoneuron 2013-49: 1-241). Click here for map of regions.


Bibref 1186 - Field Guide to Moths of Eastern North America (2005) Covell, C.V., Jr.
Bibref 1185 - Field Guide to Western Butterflies (Peterson Field Guides) (1999) Opler, P.A. and A.B. Wright

Search More Titles in Bibliography

Additional resources

USDA: Find Ulmus thomasii in USDA Plants
FNA: Find Ulmus thomasii in the Flora of North America (if available)
Google: Search Google for Ulmus thomasii


Record Modified: 2013-06-27
Research By: TWC Staff

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