Slippery Elm (Ulmus rubra)

Plantae>Magnoliophyta>Magnoliopsida>Urticales>Ulmaceae>Ulmus rubra Muhlenberg

Slippery Elm (Ulmus rubra)

Slippery Elm is a fairly common medium-large tree, named for its mucilaginous inner bark. Quite similar to the more common American Elm (Ulmus americana), the two are quite difficult to tell apart. There is no difference in the mucilage of the twigs or leaves, as far as I can tell.

Leaf shape is a clue: note how the broad leaves abruptly narrow to a long, thin point. The leaves of Slippery Elm tend to be a little more coarsely toothed. Habitat is also a clue: Slippery Elm is most abundant in rocky areas with basic bedrock, while American Elm is common in bottomland forests without regard to pH. Slippery may also occur in bottomlands, so habitat is not completely reliable to separate the two.

Caswell Co., NC 5/21/10.

Slippery Elm (Ulmus rubra)

The leaves are generally very rough-hairy above. American Elm leaves are on average smoother and shinier, but may also be rough above. Note again the abruptly acuminate leaf shape.

Caswell Co., NC 5/21/10.

Slippery Elm (Ulmus rubra)

An alternate common name is Red Elm.

Caswell Co., NC 5/21/10.

Slippery Elm (Ulmus rubra)

Leaf undersides are hairy with prominent veins.

Caswell Co., NC 5/21/10.

Slippery Elm (Ulmus rubra)

Caswell Co., NC 5/21/10.

Slippery Elm (Ulmus rubra)

Crowder's Mountain State Park, Gaston Co., NC 4/16/2011.

Slippery Elm (Ulmus rubra)

Uwharrie River slopes, Montgomery Co., NC 4/17/2011.

Slippery Elm (Ulmus rubra)

Branches are hairy.

Caswell Co., NC 5/21/10.

Slippery Elm (Ulmus rubra)

Comparison of Ulmus rubra (left) and Ulmus americana (right) growing together at the intersection of a basic slope and a bottomland. Note the difference in leaf shape, with American Elm coming to a more gradual point. American Elm also tends to be darker green and shinier above.

Caswell Co., NC 5/21/10.

Slippery Elm (Ulmus rubra)

Slippery Elm is rare in the Coastal Plain, where it occurs on outcroppings of calcium-rich marl, such as here on the shore of Lake Waccamaw.

Lake Waccamaw, Columbus Co., NC 9/28/2013.

Slippery Elm (Ulmus rubra) samaras/fruits

Fallen fruits (samaras) on Carpinus leaf. The samaras have hairless margins and are not notched at the tip.

Durham Co., NC 3/25/2012.

Slippery Elm (Ulmus rubra) samaras/fruits

Fallen fruit (samara) on Podophyllum leaf.

Durham Co., NC 3/25/2012.

Slippery Elm (Ulmus rubra)

Granville Co., NC 5/16/09.

Slippery Elm (Ulmus rubra)

The leaf bases are very lopsided, unlike those of Winged Elm (U. alata).

Durham Co., NC 5/3/08.

Slippery Elm (Ulmus rubra)

The leaves are rough above, while those of the very similar American Elm (U. americana) may be rough or smooth above, and the leaves are longer and broader than those of Winged Elm (U. alata).

Durham, NC.

Slippery Elm (Ulmus rubra)

The flowers, which are produced in March-April before the trees leaf out, are bright green, unlike the dull reddish tinged flowers of the Winged Elm. Slippery Elm samaras are hairless and not notched at the tip; those of American Elm are also green but have ciliate margins and are conspicuously notched at the tip.

Botetourt Co., VA 4/19/05.

Slippery Elm (Ulmus rubra)

Young leaves.

Botetourt Co., VA 4/19/05.

Slippery Elm (Ulmus rubra)

Bark of a medium-sized tree. Becomes more ridged with age.

Durham, NC.

Slippery Elm (Ulmus rubra)

Bark of a medium-sized tree. If you cut a cross section of the bark of American Elm, you'll see alternating pale and dark bands, lacking in Slippery Elm.

Caswell Co., NC 5/21/10.

Crowder's Mountain State Park, Gaston Co., NC 4/16/2011.