BUCKTHORN  , known botanically as Rhamnus cathartica (natural

order Rhamnaceae), a much-branched shrub reaching ro ft. in height, with a blackish bark, spinous branchlets, and ovate, sharply-serrated leaves, 1 to 2 in. long, arranged several together at the ends of the shoots . The small green flowers are regular and have the parts in fours; male and female flowers are borne on different plants . The fruit is succulent, black and globose, and contains four stones . The plant is a native of England, occurring in woods and thickets chiefly. on the chalk; it is rare in Ireland and not wild in Scotland . It is native in Europe, north Africa and north Asia, and naturalized in some parts of eastern North America . The fruit has strong purgative properties, and the bark yields a yellow dye . An allied species, Rhamnus Frangula, is also common in England, and is known as berry-bearing or black alder . It is distinguished from buckthorn by the absence of spiny branchlets, its non-serrated leaves, and bisexual flowers with parts in fives . The fruits are purgative and yield a green dye when unripe . The soft porous wood, called black dogwood, is used for gun-powder . Dyes are obtained from fruits and bark of other species of Rhamnus, such as R. infectoria, R. tinctoria and R. davurica—the two latter yielding the China green of commerce . Several varieties of R .

Alaternus, a Mediterranean species, are grown in shrubberies .

Sea-buckthorn is Hippophae rhamnoides, a willow-like shrub, r to 8 ft. in height, with narrow leaves silvery on the under-side, and globose orange-yellow fruits one-third of an inch in diameter . It occurs on sandy seashores from York to Kent and Sussex, but is not common . American buckthorns are: Rhamnus purshiana or Cascara sagrada, of the Pacific coast, producing cascara bark, and R . Caroliniana, the alder-buckthorn .