Buckthorn, a plant of the genus rham-nuSj of the order rhamnacece, comprising about 60 species, distinguished by its hermaphrodite or polygamo-dioecious flowers, 4 or 5-cleft calyx, the tube campanulate and lined with the disk; petals small or wanting, when present notched and wrapped around the stamens; ovary free, 2 to 4-celled; drupe berry-like, black when ripe, containing 2 to 4 seed-like nutlets grooved on the back. Shrubs or trees, with alternate, rarely opposite leaves, petiolate, pinnate-veined, deciduous or evergreen; stipules small and deciduous; flowers axillary, racemose or cymose. The buckthorn (R. catharticus) is a native of Europe, and has been partly naturalized in the eastern states. As it is hardy as far north as New Hampshire, and bears the knife well, it is much used as a hedge plant, for which its thick short branches and stout spines well fit it. When growing free as a standard, the buckthorn attains a height of 12 or 15 feet. The flowers are of a greenish-yellow color. The juice of the unripe berry has the color of saffron, and when ripe, mixed with alum, the pigment known as sap green is produced. The bark affords a fine yellow dye.

Medicinally the berries and inner bark are violently cathartic and purgative, and so strong are these qualities that they even affect the flesh of birds feeding upon the ripe berries. Plants are easily propagated from the seeds and grow with considerable rapidity. To make good hedges, however, it is necessary to keep them cut low for two or three years, and then if the longer free-growing shoots are intertwined with the older branches, a perfectly hardy and impenetrable hedge is procured in a few years. Among American species, R. lanceolatm and R. alnifolius are not uncommon, but neither is so easily managed as a hedge plant, nor are the berries so valuable as those of R. catharticus. In some species native to Siberia, the wood is reddish and exceedingly hard; the Mongols use it for their carved images. The wood is also used in the manufacture of charcoal for gunpowder.

Buckthorn (Rhamnus catharticus).