A deciduous shrub, Frangula alnus, native to Europe and neighboring areas of Asia and Africa, bearing glossy leaves, flowers in sessile umbels, and inedible red berries that turn black when ripe, and historically used as a laxative and to produce dyes.
also genus Frangula, especially Frangula alnus, the alder buckthorn.
especially the common buckthorn or purging buckthorn; Rhamnus cathartica.
especially genus Rhamnus,
Hippophae (family Elaeagnaceae), the sea buckthorn.