B. P. I. — 424. 



AMERICAN MEDICINAL BARKS. 



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 Pharmacopoeia — 

 number only seventeen in all, twelve of which are furnished by trees 

 and shrubs groAving in the United States either as native or intro- 

 duced species, there are many others which are nevertheless used in 

 medicine to a considerable extent by one or another school of prac- 

 titioners. All of the ;c 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 cen- 

 turies 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 con- 

 tributing 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 (Rha?ntn/s 

 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 de- 

 70075— Bui. 139—09 2 7 



