Inner bark of Slippery Elm, Ulmus rubra, is a well known mucilage, excellent for treating the throat and digestive tract. Slippery Elm is native to the USA and Canada. Adaptable to most well-drained soils. Prefers an open sunny position to partial shade. Frost resistant but drought tender. Deciduous tree, growing to 25m x 6m. Flowers are greenish and insignificant, occurring in clusters.