Page:Popular Science Monthly Volume 45.djvu/618

, and other Himalayan species, which constitutes the highly valued "rusot."

Considered from the plant's standpoint, this bitter principle, so abundantly present in its outer tissues, is doubtless to be regarded as a defense against gnawing animals, and as such, accessory to the spines which can be effective as a protection only against the larger animals which feed upon leaves. Thus, as often happens with the plants of our pharmacopœia, the very means adopted for its preservation becomes the object of its being destroyed for man's use.

But the barberry has more to contend against than the attacks of animals. As a native of regions visited by heavy storms of snow and wind, its branch system (often eight to ten feet in height), even though it be rid of its leaves through the winter, must, nevertheless, be subjected to a very considerable



mechanical strain. A glance at the vegetative organs of our plant will show with what efficiency and economy of material this bit of engineering is accomplished.

First of all it will be noticed that there are two remarkably different sorts of branches (compare Figs. 1 and 4). The one sort, long, slender, and arching, are armed with the stout spines already referred to; while the others, originating from the axils of these spines, remain very short, although bearing year after year, through the summer, each a rosette of leaves. All who have observed the effect upon our trees and shrubs of one of those storms which load everything with snow and ice must have seen that the plants which received least damage were those in which there was either unusual stoutness of material or else such an attitude and flexibility in the branches as enabled them to bend readily under a load or other strain. Now, in the branch system of the barberry bush we find all these