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Trees of Iowa: An Interactive Key

Rock Elm
(Ulmus thomasii)


Leaves are alternate, simple, double-toothed with unequal leaf bases.


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The rock elm, or cork elm, is the most important lumber tree of the elms.   It is smaller than the American elm and has a straight trunk and oblong crown.

Hardiness: zones

Growth Rate:
Moderate

Mature Shape:


Height:
80 to 100 feet

Width:


Site Requirements:


Flowering Dates: March - May

Seed Dispersal Dates: May - June

Seed Bearing Age: 20 years

Seed Bearing Frequency: every 3 to 4 years

Seed Stratification:
Rock Elm TwigRock Elm Leaves

The leaves are 2-1/2 to 4 inches long, smooth above, hairy below.  Leaves are shiny dark green above and light green below.  The larger twigs have corky, irregular, prominent ridges. The brown buds are broadly rounded and velvety.  The characteristiccorky  ridges are present on the small trunks and branches and on largertrunks the bark is broken into narrow, interlacing ridges.

The waferlike fruit is winged, contains one seed and is similar to the fruit of other elms but is narrower and velvety.

 

Click on a thumbnail image below to view a larger picture.
Rock Elm Leaves Rock Elm Twig