Most species in the rhamnaceae (buckthorn) family are trees or shrubs; nearly 1,000 worldwide but just two in the UK: buckthorn and alder buckthorn. Leaves are simple, either opposite or alternate, often modified into spines, while flowers are small and clustered, with sepals, petals and stamens numbering either four or five. Stamens are positioned opposite the petals. Fruits are berrries or nuts.
