Buckthorn is a type of shrub or small tree that is native to Europe, Asia, and North America. Cascara, with seven letters, is the dried bark of the buckthorn tree, which is used as a laxative. SUMAC, with five letters, is a type of shrub or small tree that produces red berries and is related to the buckthorn. Cascaras, with eight letters, is an alternative name for cascara. Rhamnus, with seven letters, is a genus of plants in the buckthorn family. SLOE, with four letters, is a type of plum that is related to the buckthorn.