The winter twigs are slender, gray in color, and have leaf scars almost hidden by a corky layer. The flower buds are larger and often rounder than the leaf buds. The dark brown to reddish brown bark is moderately thick, with shallow, slightly irregular furrows that separate the flattened ridges and uniform in color in cross section, unlike the American elm. Slippery elm seems an odd name for a tree with rough leaves. Its name refers to the trees inner bark which is mucilaginous and has soothing properties and was once widely used as a sore throat remedy, a wound dressing and as a poultice.
Slippery elm is native to the entire state.
It grows best on moist, rich soils of lower slopes, streambanks, river terraces, and bottomlands, but it is often found on drier sites as well. Because of the diversity of sites where it grows, the associated species list includes most other tree species in Iowa. On bottomlands, common associates include silver maple, cottonwood, green ash, hackberry, and boxelder. On better sites, associates include red oak, black walnut, white ash, and basswood. Slippery elm is susceptible to Dutch elm disease, but the species is still very common in forest edges and in the woodland understory because it is such a prolific producer of seed and young trees are less susceptible to the disease.