trace, but the species is so widely distributed that intervention by people 

 must have occurred. With the possible exception of D. alata, this species 

 is the most varied of the Asian edible yams. Its races occur from the 

 mountains to the sea and from the hottest Tropics almost to the temper- 

 ate regions. This species needs study, but such research can only be done 

 after it has been collected over its wide range of distribution. Changes in 

 Asia, destruction of the forest, changes in food habits, loss of cultivars, 

 and the rapid distribution of cultivars because of high-speed transporta- 

 tion may make it impossible to trace further the history of this species 

 that has been so closely related to the activities of people. 



With respect to D. niun miliaria , less is known about its origin. 

 Papua New Guinea and Indonesia are where the most variation is seen. 

 D. transversa is known only from a few islands of the South Pacific. 



Although principally a West African species, D. dumetoriim is a 

 famine food in Sudan {8). This use suggests its presence in considerable 

 quantities. D. dumetorum occurs in the eastern deserts of Ethiopia and 

 is common wild and cultivated as far west as Sierra Leone and is seen in 

 Senegal (^). To the south, it is common in Zaire, is harvested from the 

 wild in Rhodesia and Transvaal, South Africa, but is apparently un- 

 known on the southeast coast of Africa. D. dumetorum may occur in the 

 deserts of Asia Minor but is not seen elsewhere in the Tropics. 



Wild yams of D. hispida and D. pentaphylla have recently been 

 collected in India, apparently the most western extension of these 

 species. D. pentaphylla is believed to have reached Hawaii in pre- 

 Columbian times. It reaches north to the Himalayas and south almost to 

 Australia and is common on many islands of the Pacific. D. pentaphylla 

 has not found a home in the Tropics of other continents, although it has 

 been sporadically introduced. 



D. h ispida is common in Southeast Asia and Indonesia and extends 

 at least to Papua New Guinea and the Philippine Islands. Probably, it 

 is cultivated principally in Java. 



D. nmyimularia is now principally a yam of the South Pacific, 

 including Papua New Guinea. It extends throughout Indonesia and' is 

 found wild in Malaysia (5). It is not known in other parts of the Tropics. 



D. transversa, cultivated before only in the South Pacific, has now 

 gained a foothold in the French West Indies. 



BOTANY 



Classification 



All the minor yams belong to the genus Dioscorea, the principal 

 genus of the family Dioscoreaceae. The family is usually classified among 

 the monocotyledons, although some evidence of a second cotyledon has 

 been found. The family is characterized by rhizomes, usually reduced to 

 a nodeless structure. Male and female flowers, usually on separate 

 plants, are small and usually inconspicuous, although the inferior ovary 



7 



