The Buckthorns (Rhamnus).
Our two native species of Buckthorn are shrubs of from five to ten feet in height. In this one respect they agree; in almost all others they differ. Both are Buckthorns in name, but the Breaking Buckthorn (Rhamnus frangula) is quite unarmed, whilst many of the branchlets of the Purging Buckthorn (Rhamnus catharticus) are hardened into spines.
The Purging Buckthorn is distinguished by its stiff habit, and by some of the leaves being gathered into bundles at the ends of the shoots. The leaves are egg-shaped, with toothed edges, and of a yellowish-green tint, with short leaf-stalks. The yellowish-green flowers are very small, and will be found both singly and in clusters from the leaf-axils. There are a four-cleft calyx, four petals, four stamens, or four stigmas, for the sexes are usually on separate plants. The fruit is black, round, and about a quarter of an inch across, containing four stones. These so-called "berries" are ripe in September. Formerly they were much used as a purging medicine, but of so violent a character that their use has come to be discouraged, and the safer syrup of Buckthorn is prescribed instead. The juice of these berries is the raw material from which the artist's sap-green is prepared. It may be found in woods, thick hedgerows, and bushy places on commons southward of Westmoreland, showing a decided preference for chalky soils. In Ireland it only occurs rarely.
The Breaking Buckthorn (Rhamnus frangula) is also known