COCA 25 



The midrib is reddish brown, depressed on the upper surface and 

 surmounted by a raised ridge ; on the under surface on either side 

 of the midrib a distinct, raised, curved line runs from the base to the 

 apex of the leaf. This line is formed in the young leaf, each half of 

 which is inrolled (involute) in the bud and forms a ridge closely 

 applied to a similar ridge on the other half. Although the leaf is 

 not thick it is by no means fragile, the lateral veins and veinlets being 

 comparatively strong, and hence prominent on the upper surface 

 (fig. 15). When a transverse section is examined under the microscope 

 most of the epidermal cells of the under surface will be seen to project 

 in the form of small papillae ; in surface view these appear as circular 

 rings. 1 This peculiarity, although exhibited by other species of 



FIG. 15. A, under surface of Bolivian coca leaf ; J3, of Peruvian coca 

 leaf, showing the difference in the veinlets. Magnified. 



Erythroxylum, is so unusual as to render it of considerable diagnostic 

 importance. The leaves have a faint but characteristic odour. 4The 

 taste is slightly bitter, followed by a feeling of numbness in the mouth 

 and throat. The small, oblong-ovoid, dark brown, pointed fruits are 

 occasionally found in the drug. 



Peruvian or Truxillo coca leaves are rather smaller than the Bolivian ; 

 they are pale green in colour and are more fragile, hence they are 

 usually more or less broken. On the under surface the two curved 

 lines are much less distinct ; on the upper surface the ridge above 

 the midrib is less marked ; on the under surface the veinlets are 

 less prominent and the midrib green in colour. These leaves fre- 

 quently contain an admixture of the carefully picked and dried flowers 

 of a species of Inga easily recognised by their yellowish brown, tubular, 

 hairy calyx and numerous deep red filaments forming a plume ; this 

 is an intentional addition, made apparently with the view of 



1 Compare Greenish and Collin, Anatomical Atlas, p. 63. 



