Slippery Elm

Introduction • Trees Index • Glossary

Slippery Elm in summer

Slippery Elm (Ulmus rubra)

A deciduous tree from the Elm Family (Ulmaceae)

Slippery Elm is similar in many ways to American Elm, but differs in its branching habit (it branches higher on the trunk, with fewer main branches), the texture of its slightly larger leaves (they are sandpapery on both sides), and the color of its interior heartwood (reddish-brown). While its geographic distribution is almost the same as American Elm (eastern and central United States), Slippery Elm is more commonly found in the slightly drier soils of uplands, although it may be found growing side by side in mesic sites with American Elm. Slippery Elm is also subject to attack by Dutch Elm disease, but not to the extent of American Elm.
Slippery Elm is named after its slick, mucilaginous inner bark, which was chewed by the Native Americans and pioneers to quench thirst when water was not readily available. Also known as Red Elm (in reference to its reddish brown heartwood), this tree may reach 60 feet tall by 50 feet wide, when found in the open. As a member of the Elm Family, it is related to Hackberry, Zelkova, and the many other Elms.

Planting Requirements - Slippery Elm prefers moist, deep, rich soils of variable pH, but is often found in soils that are dry and of average composition. Its winged seeds readily disperse over a wide area in spring, and the root structure of seedlings is initially taprooted, but quickly develops into a fibrous system that transitions to shallow roots with age (as is typical of species that like moist soils). It thrives in full sun to partial sun, and is found in zones 3 to 9.

Potential Problems - Slippery Elm is also subject to the ravages of Dutch elm disease and elm phloem necrosis, like American Elm, but not quite as severely. In addition, the Elms in general are subject to numerous pests and pathogens which adversely impact their foliage, bark, wood, and roots, with the effects ranging from seasonal cosmetic blemishes, to serious threats to tree health.

Leaf Identification Features

Like American Elm, the alternate leaves of Slippery Elm have asymmetrical bases, doubly serrated margins, and prominent veins that run straight out to the edge of the leaf (left). Slippery Elm has leaves that are usually larger and wider as compared to the more common American Elm. Leaves are broadly elliptical to ovate, and are sandpapery rough on both the upper and lower leaf surfaces (due to heavy pubescence). Fall color is usually green and chartreuse, with occasional golden or yellow leaves (right) interspersed in the canopy.

Other Identification Features

Slippery Elm is one of the first trees to come into flower, similar to American Elm in the appearance of its floral buds and expanded flowers (upper left). The perfect flowers soon develop into larger, more rounded samaras as compared to American Elm, and usually do not have any notch, or sometimes have a hint of a notch (upper right). Fruits have small hairs in the center of the flattened fruit, on both sides, where the central seed is located, but not on the samara edges. The fruits abscisce soon after maturation in mid-spring.
Twigs of Slippery Elm have two types of buds, easily distinguished in late winter. The floral buds (already beginning to swell) occur at the base of the previous season's twig growth, while the vegetative buds remain dormant for a longer period of time, and are at the top of the twig (upper left). Slippery Elm is known for the hairiness on its twigs and buds (lower left), while American Elm has smooth twigs and buds. Twigs have a mucilaginous inner bark when chewed, briefly quencing thirst and giving this tree its common name.
The bark of Slippery Elm develops flattened ridges with intervening furrows, having a light gray-brown coloration. Ridges are straight on both younger and mature bark, and rarely interlace (lower right).
Slippery Elm has the same basic vase shape as American Elm, but often branches higher and with fewer large branches (top photo). Its branchlets also remain ascending or somewhat horizontal, and usually do not weep back to the ground, as in American Elm.

© The Ohio Department of Natural Resources and The Ohio State University Department of Horticulture and Crop Science, 2002

Leaf Identification Features
	Like American Elm, the alternate leaves of Slippery Elm have asymmetrical bases, doubly serrated margins, and prominent veins that run straight out to the edge of the leaf (left). Slippery Elm has leaves that are usually larger and wider as compared to the more common American Elm. Leaves are broadly elliptical to ovate, and are sandpapery rough on both the upper and lower leaf surfaces (due to heavy pubescence). Fall color is usually green and chartreuse, with occasional golden or yellow leaves (right) interspersed in the canopy.
Other Identification Features
	Slippery Elm is one of the first trees to come into flower, similar to American Elm in the appearance of its floral buds and expanded flowers (upper left). The perfect flowers soon develop into larger, more rounded samaras as compared to American Elm, and usually do not have any notch, or sometimes have a hint of a notch (upper right). Fruits have small hairs in the center of the flattened fruit, on both sides, where the central seed is located, but not on the samara edges. The fruits abscisce soon after maturation in mid-spring. Twigs of Slippery Elm have two types of buds, easily distinguished in late winter. The floral buds (already beginning to swell) occur at the base of the previous season's twig growth, while the vegetative buds remain dormant for a longer period of time, and are at the top of the twig (upper left). Slippery Elm is known for the hairiness on its twigs and buds (lower left), while American Elm has smooth twigs and buds. Twigs have a mucilaginous inner bark when chewed, briefly quencing thirst and giving this tree its common name. The bark of Slippery Elm develops flattened ridges with intervening furrows, having a light gray-brown coloration. Ridges are straight on both younger and mature bark, and rarely interlace (lower right). Slippery Elm has the same basic vase shape as American Elm, but often branches higher and with fewer large branches (top photo). Its branchlets also remain ascending or somewhat horizontal, and usually do not weep back to the ground, as in American Elm.