BUCKTHORN (Rho nolus). A genus of shrubs or small trees of the order Rhanmacem. They are numerous, and natives of most of the tropical and temperate regions of the world. The common buckthorn (Rhanomus cathartiea) is a deciduous shrub or low tree, frequent in Eng land and in other parts of Europe and the north of Asia. The leaves are ovate, crenate. and bright green; the branches spiny; the llowers small, yellowish-green and densely clustered ; male and female flowers on separate plants; the berries about the size of peas, globular, blue black, nauseous, and violently purgative. They were formerly much used in medicine, but now more rarely, and only in the form of a syrup prepared front their juice. They supply the sap green or bladder-green of painters. The bark affords a beautiful yellow The buckthorn is sometimes planted for hedges, but is of too straggling a habit. The alder buckthorn, or berry-bearing alder (llhantnus frangula), is also a native of Great Britain and is frequent in woods and thickets throughout Europe. It is a shrub, rarely a small tree, with spineless branches, oval entire leaves, and small, whitish axillary flowers, which are, in general, somewhat clustered. 'The charcoal of the wood is light. and is used for the preparation of gunpowder. The bark, leaves, and berries are used for dyeing; the bark for dyeing yellow, and, with preparations of iron, black; the unripe berries to dye wool green and yellow; the ripe berries to dye it bluish-gray, blue, and green. There are about a
dozen native species in the United States, one of the most important being Rhamnus purshiana of the Pacific States, where it is known as Cascara sagrada. It is a tree 15 to 20 feet in height and its hark is extensively used in medi cine. It contains tannin, three resins, and other principles, and has a considerable reputation as a tonic, ve•mifuge, and purgative. Rhamnus Californieu, an inferior species, is also some times called Cascara sagrada. Dyer's buckthorn (Rhamnus infectoria) is a low' shrub, abundant in the south of Europe, whose unripe fruit yields a brilliant yellow dye. The berries and inner bark of lamantnus tinctora, a native of Hungary, are also used in dyeing; as also are the berries of Rhamilus samatilis, a proeumbent shrub, grow ing among rocks as far north as Switzerland. The 'French berric4,' 'Avignon berries,' or 'yellow berries' of dyers are the fruit of Rhamnus injectoriu, sa.ratilis, olcoidcs, and alaternus. The sea-buckthorn is a shrub of a different genus and order. (See SW A Bum-elia lunugi aosa, a *mall tree with hard wood and useful for hedges, is also called buckthorn.