70 THE SWEET POTATO. 



out in May. The varieties, received under more 

 than a hundred different names, were studied in the 

 same systematic fashion as the thirty-five varieties 

 of the previous year. 



As was expected, the majority of the characters 

 noted proved unreliable. The abundance of the 

 latex and the color of the leaves, for example, while 

 distinctly variable with the varieties, were not con- 

 stant enough to be used as a characteristic. By 

 studying all the plants of every variety planted 

 (about 15-30 plants on an average), the writer came 

 to the conclusion that certain characters were suffi- 

 cient to distinguish all varieties which could be dis- 

 tinguished at all by the closest macroscopical obser- 

 vation. Microscopical characters were not utilized 

 because they could not be easily applied, and because 

 the writer is not prepared to say that the micro- 

 scopical differences found are constant. 



The character by which the groups can be sep- 

 arated most readily is, doubtless, the shape of the 

 leaf. Mr. Price recognized this in his system of 

 classification, and the author has adopted his terms, 

 "round-leaved" and '* cut-leaved. " The shape of 

 the leaves enables one to divide all varieties at hand 

 into five main groups. 



The first group comprises all varieties with "cut" 

 leaves. As "cut" leaves are counted all those in 

 which the projecting lobes constitute almost the 

 entire leaf surface, so that little remains when all 

 the lobes are cut off at their bases by cuts perpen- 

 dicular to their median lines. In all but one or two 

 varieties it is very easy to tell whether the leaf 

 is cut or not; but even if that should be impossible, 

 that fact does not interfere much with the determina- 

 tion of a variety, as will be seen later. 



