Figure 6. — Tubers of D. dumetorum.. 



PN-6372 



sis also have chromosome numbers based on both 9 and 10 (i^). D. 

 pentaphylla has been reported to have 40, 80, and 144 chromosomes. 

 The latter number, approximating 16-ploid, is untrustworthy. Counts 

 have not been found in the literature for D. nummularia. 



Probably, the five minor species under consideration here have 

 been slightly improved by primitive selection. Of these, perhaps the 

 most ennobled is D. dumetorum, with its poison-free races, followed 

 closely by D. pentaphylla, with its extreme diversification. There are no 

 historical records to show how improvement might have occurred, and 

 there are no present attempts to improve these species. 



CULTURE 

 Cultivars 



For each of the five minor species considered here, named cultivars 

 exist. These have been selected by primitive farmers for special charac- 

 teristics and are propagated vegetatively. Little is known of such culti- 

 vars, and they are held principally by subsistence farmers. It is difficult 



14 



