buckthorn, common name for some members of the Rhamnaceae, a family of woody shrubs, small trees, and climbing vines widely distributed throughout the world. The buckthorns (several species of the genus Rhamnus ) and the jujube ( Ziziphus jujuba ) are cultivated for their ornamental foliage. The jujube was also used locally and exported for use in confectionery and as a flavoring, now largely replaced by artificial flavorings. The lotus of Tennyson's "Lotus-Eaters" is thought to have been the jujube. Other members of the family yield dyes and a limited amount of lumber, e.g., cogwood, a hardwood. Other American species of Rhamnus are the redberry, the Indian cherry, and, in California, Rhamnus purshiana, which yields the purgative cascara sagrada. Buckthorn is classified in the division Magnoliophyta, class Magnoliopsida, order Rhamnales.