On the other hand, introduced yams from the Old World (6)^ 

 have tended to displace American species, and cultivation of the 

 minor ones is rapidly disappearing. Only a good species could com- 

 pete with the better Asian and African introductions. Of the edible 

 American species, only Z). trifida L. merits special attention. A 

 cultivated species today, it is appreciated as a special yam where- 

 ever it is grown; and in a few regions, such as the French West 

 Indies, it continues to compete with introduced and more prolific 

 yam species. 



History and Origin 



D. trifida is believed to have been domesticated in South 

 America. It presently ranges from eastern Peru through tropical 

 Brazil, to the Guyanas, and beyond to the islands of Trinidad and 

 Tobago, and all of the West Indies (^) . Only a few forms of the 

 species are known in the Greater Antilles, suggesting that these 

 islands represent the extremes of the distribution pattern. A linr^ 

 ited number of named varieties are recognized in the westernmost 

 parts of the range (eastern Peru) . For example, nine named clones 

 are to be found in the gardens of the Aguaruna Jivaros (a primi- 

 tive tribe of Peru) (i^). In the Guyanas, a wide range of culti- 

 vated as well as wild forms exists, and this area may be thought of 

 as the probable center of origin. In this region, varieties normally 

 flower and seeds are produced abundants, providing the oppor- 

 tunity for evolutionary changes through the sexual process and for 

 improvement by cross-breeding methods. D. trifida may be the 

 only cultivated yam species to retain sexuality fully. 



Among the many tribes that utilize D, trifida, none use it as a 

 staple, in part because of competition with the ever-present cas- 

 sava and in part because of the seasonal limitations of the species. 

 Since in any region a mature tuber is available only during a short 

 season, the species cannot be utilized as a staple food except for 

 brief periods. 



Geographic Distribution 



The present geographic distribution is not much more ample 

 than the pre-Columbian. D- trifida has been introduced on a small 

 scale in Sri Lanka and apparently has been widely received. It is a 

 minor yam in New Caledonia, to which it came from the New 

 Hebrides. If found in other tropical areas of Asia or Africa, it has 

 not received any special attention. 



The potential for developing better D. trifida varieties has 



2 Italic numbers in parentheses refer to items in "Literature Cited," p. 24. 



3 



