TROPICAL YAMS 

 AND THEIR POTENTIAL 



Part 5. Dioscorea trifida 



By Franklin W. Martin and Lucien Degrasi 



INTRODUCTION 



Of the 9 to 12 principal cultivated species of yam, none is less 

 well known than the American species Dioscorea trifida L., or 

 cushcush (fig. 1). Nevertheless, in those areas where it is pro- 

 duced, D. trifida is known as the best of the yams because of its 

 flavor and cooking qualities. Although only of minor importance 

 in the New World, the potential of cushcush should be fully 

 examined. 



Yams have never achieved in America the important position as 

 a staple food that they obtained in Africa, Asia, and the islands of 

 the Pacific. The same purpose has been served by other species 

 such as cassava {Manihot esculenta Crantz) , sweetpotato (Ipomoea 

 batatas Poir), and tanniers or yautias (Xanthosoma spp.). As 

 important elements of the tropical forests, however, yam species 

 were plentiful. Experimentation led to the exploitation of some 

 yam species (D, composita Hemsl.) as fish poisons. The vigorous 

 species D. convolvulacea Schlecht. et Cham, has been distributed 

 widely throughout Central America as a minor cultivated or wild 

 tuber crop. In Guatemala, it is known as ''madre de maiz" and 

 used chiefly as a famine crop. The species D. dodecaneura Veil, 

 may have been even more widespread in South and Central Amer- 

 ica. A few even less important edible species are D. adenocarpa 

 Mart., D. piperifolia Willd., D. trifoliata Grisebach., and D. sinuata 

 Well. In addition, tubers of a species of a related genus, Rajania 

 cordata L., were harvested from the wild and occasionally culti- 

 vated on the islands of the Caribbean. The species is a famine food 

 in Puerto Rico. It is highly likely that other edible species of yam 

 also occur. 



' Horticulturist. Mayai;uez Institute of Tropical Agriculture, Science and Education 

 Administration — Federal Research Staff— U.S. Dej^artment of Agriculture, 

 Mayagiiez, P.R. 00708, and plant geneticist. Station d'Amclioration des Plantes, 

 Institut National de la Recherche Agronomique, Domaine Duclos, Petit-Bourg, 

 Guadaloupe. 



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