Introduction.
Among the manifold uses of the trees of our forests not the least important is the utilization of their barks for medicinal purposes.
While the “official” barks—that is, those that are recognized in the Eighth Decennial Revision of the United States Pharmacopœia—number only seventeen in all, twelve of which are furnished by trees and shrubs growing in the United States either as native or introduced species, there are many others which are nevertheless used in medicine to a considerable extent by one or another school of practitioners. All of the “official” barks are described in this bulletin, and an effort has been made to include such “nonofficial” ones as seemed to be most in demand, judging from the trade catalogues of wholesale dealers in crude drugs, but a number of others that are not so much used have been omitted on account of lack of space. The number of drugs fully described is thirty-five, but under many of the descriptions closely related species are also briefly treated.
Many factors have contributed to the destruction of our forests. Beginning with the settlement of this country, when land had to be cleared of timber to make way for homes, and on through the centuries there have been steady and increasingly heavy drafts upon our natural forest resources by an increasing population and the building up of various new enterprises, and until within very recent years with little or no thought for the needs and welfare of generations to come. In the collection of barks, too, may be seen another instance contributing in a measure to the depletion of our forests; for too often trees are felled and killed outright simply for the sake of obtaining the bark, or a tree is peeled to such an extent that death is certain to result. When it is considered that of cascara sagrada (Rhamnus purshiana) alone about 100,000 trees are annually sacrificed, and that the oak, pine, elm, birch, poplar, willow, and larch all contribute their quota of bark, it will be seen that at no very distant date more careful methods of bark collection and the replanting of now denuded areas will be needed. The Forest Service of the United States Department of Agriculture has issued Forest Planting Leaflets, giving full information in regard to the planting and propagation of many of our forest trees, and anyone interested in the subject can have these leaflets for the asking.
The statements herein regarding medicinal uses are based on the information contained in various dispensatories and other works relating to materia medica, and in a publication of the character of this bulletin can, of course, be referred to only in the most general manner. It is not the purpose herein to prescribe the use of any of these barks for medicinal purposes; such use should be made only under the direction of a physician.
The writer is indebted to Mr. George B. Sudworth, Dendrologist of the Forest Service, for an examination of the manuscript and for the use of a number of photographs taken by him and other members of that Service.
Other illustrations in this bulletin have been reproduced from photographs taken from nature by Mr. C. L. Lochman, and use has also been made of a number of illustrations found in the Handbook of the Trees of the Northern States and Canada, by Mr. R. B. Hough.
The writer also wishes to gratefully acknowledge information of various kinds furnished by wholesale drug dealers.