» For the genus Hippophaë, see Sea-buckthorn. The Buckthorns (Rhamnus) are a genus (or two genera, if Frangula's treated as distinct) of about 100 species of shrubs or small trees from 1-10 m tall (rarely to 15 m), in the buckthorn family Rhamnaceae. They're native throughout the temperate and subtropical Northern Hemisphere, and also more locally in the subtropical Southern Hemisphere in parts of Africa and South America. Some species are invasive outside their natural ranges. Both decidu… (More on Buckthorn)