CRUDE DRUGS. 



523 



the younger bark the medullary rays are from 4 to 7 cells wide; 

 otherwise the pieces resemble Frangula. 



Fig. 229. 



Bark of Khamnus Purshiana showing large whitish patches of lichens, 

 and numerous lens-shaped lenticels. 



RHAMNUS PURSHIANA.— CASCARA SAGRADA.— 

 The bark of Rhamnus Purshiana (Fam. Rhamnacese), a shrub 

 indigenous to Northern California, Washington, Oregon and the 



