[Illustration: _Pl. 88._ Breaking Buckthorn.]
[Illustration: _Pl. 89._ Fruits of Purging Buckthorn.]
[Illustration: _Pl. 90._ Fruits of Breaking Buckthorn.]
[Illustration: Purging Buckthorn. A, flowers.]
The Breaking Buckthorn (_Rhamnus frangula_) is also known as the Berry-bearing Alder, its leaves, with their lateral veins, presenting something of the appearance of the Alder. Its more slender stems are purplish-brown in hue, and _all_ the leaves are arranged alternately up the stems. The leaves further differ from those of _R. catharticus_ in having plain, un-toothed edges, and their veins parallel one to another. The flowers are similar in size to those of the other species, but are whiter, less yellow, fewer in number, and on longer stalks. The parts of the flower, too, are in fives instead of fours; and the "berry," though similar to the previous species, is much larger (half-inch diameter). In an unripe condition these fruits yield a good green dye, much used by calico printers and others. The wood made into charcoal is said to be the best for the purposes of the gunpowder makers, who know it by the name of Black Dogwood. The straight shoots of both species are used for forming walking and umbrella sticks, and those of longer growth for pea and bean sticks.
The Brimstone butterfly (_Gonepteryx rhamni_) lays its eggs on the leaves of _R. frangula_, upon which the larva feeds. The name Buckthorn appears to be due to an ancient misunderstanding of the German name Buxdorn, which should have been translated Box-thorn.
With the single exception of the Hazel, all our native fruit-trees are members of the extensive and beautiful Rose family. Before Roman invasions brought improved and cultivated varieties, our "rude forefathers" must have been glad to eat the Sloes, Crabs, and Wild Cherries that are now regarded as too terribly crude and austere, in an uncooked condition, for any stomach but that of the natural boy, which appears capable of surviving any ill-treatment. Some authors have regarded the Wild Plum and the Bullace as being specifically distinct from the Sloe and from each other; but the modern view is that their differences only entitle them to rank as sub-species of the Sloe, and as such they will be regarded here.