TROPICAL YAMS AND THEIR POTENTIAL, PART 3 



11 



PN-4441 



Figure 5. — Irregular tubers of a Feo group yam. (One-fourth actual size.) 



tive, intermediate. In another 

 study Rhodes and Martin used the 

 techniques of numerical taxonomy 

 to define groups in a less arbitrary 

 fashion (26) . The primitive group 

 was divided into two easily dis- 

 tinguished subgroups. In this 

 study the difficulty of grouping 

 was revealed by the special tech- 

 niques used. On a multidimensional 

 graph made possible by the prin- 

 cipal-components method, few va- 

 rieties were found to occur in 

 recognizable clusters. The char- 



acteristics found by the authors to 

 be useful in classifying varieties 

 and their method of rating are 

 given in table 1. 



The classification of D. alata 

 varieties into groups is probably 

 always artificial and serves best 

 the needs of particular investiga- 

 tors. The family tree of the species 

 would probably consist of a net- 

 work of anastamosing branches, a 

 few small limbs, and many twigs 

 now separated from the parental 

 trunk. Thus, the bewildering array 



