Rhamnaceae

Rhamnaceae, the buckthorn family, is a diverse group of flowering plants in the order Rosales. The family comprises about 50–60 genera and roughly 900 species. Members are predominantly shrubs and small trees, with some lianas, and they are widely distributed in tropical, subtropical, and temperate regions. Leaves are generally simple and alternately arranged, often with small stipules. Flowers are typically small and inconspicuous, usually with five tepals and five members (sepals and petals), and fruit types vary from drupes to dry capsules or berries.

Two major subfamilies are commonly recognized: Rhamnoideae and Ziziphoideae, though the circumscription of genera varies among treatments. The fruits are often drupes or capsules; seed dispersal mechanisms range from animal-mediated to gravity in different lineages. The family includes several genera of economic and ecological importance, notably Rhamnus (buckthorn), Ziziphus (jujube), Ceanothus (California lilac), Gouania, Colubrina, and Paliurus (Christ’s thorn). Ziziphus jujuba is cultivated for its edible fruit in many regions, while some Rhamnus species have been used in traditional medicine and as laxatives.

Rhamnaceae is cosmopolitan, with the highest diversity in tropical Africa and Asia, and notable representation in the Americas and Europe. Some species, such as Rhamnus cathartica, have become invasive in parts of North America. In horticulture, several genera are valued for ornamental shrubs and small trees. Modern phylogenetic studies place Rhamnaceae within Rosales, with relationships among genera clarified through molecular data.