Methods of numerical taxonomy were used to classify 97 cultivars of West African yam, Dioscorea rolundata and D. cayenensis. Of 75 characteristics used, 16 were found capable of discriminating group and describing group differences. Nine groups were delineated that could be arranged in a phenetic tree illustrating their relationship. These are interconnected by anastamosing branches that may represent hybridizations. The group then merge into two main trunk which represent the traditional names D. rotundata and D. cayenensis. Nevertheless, the interrelations of the groups and the inexact mergence suggest that in fact all belong to one highly evolved complex species.