FOLIA DIGITALIS. DIGITALIS. 



185 



The absence of calcium oxalate crystals distinguishes 

 this from all other narcotic herbs. 



Adulterations and Substitutions. — Verbascum leaves 

 from Verbascum phlomoides, L., and V. thapsifonne, 

 somewhat resembling digitalis, are thicker and, on the 

 under side, more densely hairy. Microscopically they 



Fig. 47. — Digitalis in Powder. 



H, Hairs; G, glands; Mes, mcsophyll, seen on end; Tr, tracheids; 



U.E, upper epidermis; L.E, lower epidermis; V, vessels. 



are readily distinguished by their branched star-shaped 

 hairs. 



The leaves of Symphytum officinale, L., are entire, 

 rough-haired, and without bitter taste; those of Inula 

 conyza, D. C, are entire or sharply serrate, with thicker- 

 walled hairs than those of digitalis (Moeller). 



In powder the drug is adulterated with belladonna, 

 stramonium, and hyoscyamus. All these contain calcium 



