Slippery elm (Ulmus rubra) is a species of tree found primarily in the eastern and central United States. It gets its name from its inner bark, which forms a slick gel when wet due to a high abundance of mucilaginous polysaccharides.
Slippery elm bark has a history of use as a treatment for pharyngitis (sore throat) and various gastrointestinal (GI) ailments, although there is very little research to support its benefits for these conditions.