The slippery elm is a native deciduous tree known for it slippery inner bark. The tree has been used medicinally for centuries, first by native Americans and can still be found today in health food stores. It is commonly found in flood plains and along rivers and other areas of high moisture. The plant is susceptible to Dutch elm disease, but not to the degree of its relative, the American elm which has been devastated by the illness.
Slippery elm has leaves that alternate long its branches. They are oval and pointed at the tip with serrated margins and a rough finish on the surface. The underside can be hairy. Each leaf is from 4 to 7 inches long and medium green in color. The flowers of the tree bloom in early spring and hang in little green, hairy clusters. The seeds are flat and winged and are broadcast by the wind. The bark is dark reddish-brown and furrowed deeply. The name of the tree is derived from the inner bark, which is moist and very slippery.
This tree grows quickly, often adding more than two feet of growth per year and grows well in hardiness zones 3 through 8. Slippery elm is a long-lived tree that may exceed 200 years of age. The trunk of a mature tree can reach up to two feet in diameter.
Slippery elm is medium-sized and can grow up to 80 feet tall. It has a wide crown that can reach 50 feet across with a relatively flat-topped canopy. The tree's shape is not quite a well-formed as that of the American elm. The branches are open and mostly horizontal.
The tree grows commonly in wetter environments and prefers moist, but well draining, acidic soils. It does have a certain amount of drought tolerance. The plant prefers full sun, although it will tolerate partial shade. Propagation is usually by seeds or cuttings, although slippery elm is not generally grown horticulturally and is often considered a weed tree in the landscape.
Slippery elm is often used as an ingredient in natural remedies as a treatment for sore throat. The bark of the elm contains mucilage, a gluey substance that coats the throat and reduces irritation. The wood of slippery elm is tough, heavy and durable and is used for furniture, paneling and wooden containers. It is often used for fence posts, due to its resistance to rot.