tubers, the frequently large number of tubers that are too small, 

 and the relatively narrow adaptation of the species are negative 

 features perhaps more difficult to eliminate. Recent hybrids 

 produced in Guadeloupe suggest that the problems are not 

 insurmountable. 



In order to realize the potential of D. tHfida, a comprehensive 

 effort to obtain a full range of germplasm would be desirable. This 

 germplasm should then be evaluated carefully under several en- 

 vironments, and could serve as a basis for improvement of the 

 species for a wide range of environments. D. trifida must be dis- 

 tributed much more widely, preferably as seed so that selections 

 could be made in each environment. The junior author now dis- 

 tributes seeds of D. trifida on request so that breeding can be 

 initiated in many localities. 



LITERATURE CITED 



(1) Arnolin, R. 



1973. Remarques generales sur la diffusion de deux nouvelles varietes 

 de cousse-couche (D. trifida) en Guadeloupe et Martinique. 

 Nelles Maraicheres et Vivrieres de Tlnstitut National de la 

 Recherche Agronomique aux Antilles, Nos. 7-8, pp. 111-112. 



(2) , Poitout, R., and Degras, L. M. 



1973. Yams plantation density trials in Guadeloupe. Proc. 11th Annu. 

 Meet. Caribb. Food Crops Soc, Barbados, 3 pp. 



(3) Ayensu, E. S. 



1972. Anatomy of the monocotyledons. 182 pp. Clarendon Press, 

 Oxford. 



(4) . Brucher, H. 



1968. Sudamerrika als Herkunftsraum von Nutzpflanzen. In W. Junk 

 (ed.), Biogeography and Ecology in South America. Vol. 1, 

 pp. 251-300. Junk N. V. Publishers, The Hague. 



(5) Burkill, I. H. 



1960. The organography and the evolution of Dioscoreaceae, the fam- 

 ily of the yams. J. Linn. Soc. Lond. (Bot.) 56(367) : 319-412. 



(6) Canals, S. 



1956-7. Las Dioscoreas cultivadas (names) y su introduccion en el 

 Nuevo Mundo. Runa 8: 28-42. 



(7) Degras, L. 



1969. Queiques donnees sur la variabilite de descendance d'igname 

 cousse-couche (D. trifida spp.). Proc. 7th Annu. Meet. Caribb. 

 Food Crops Soc, Guadeloupe-Martinique, pp. 59-65. 



(8) 



1970. Morphology, physiology and selection in three tropical tuber 

 crops. Proc. 2d Int. Symp. Trop. Root Crops, Hawaii, 1 : 163-165. 

 (9) , Arnolin, R., and Poitout, R. 



1972. Principal yams introduced and grown in the French West Indies. 

 Proc. 10th Annu. Meet. Caribb. Foods Crops Soc, Puerto Rico, 

 pp. 93-97. 



(10) , Arnolin, R., and Poitout, R. 



1973. Selection de I'igname cousse-couche (Dioscorea trifida L.) 3d 

 Int. Symp. Trop. Root Crops, Ibadan, Nigeria. [In press.] 



24 



