206 

 204.-" YAMS." 



(Dioscorea Species.) 



Under the name " Yam" ai-e cultivated several species of Dios- 

 corea which furnish the major portion of the food supply of the native 

 population, besides being generally used by the middle and upper 

 classes. Our last crop was planted in July, 1895, and harvested in 

 February, 1896, or seven months from planting. A reference to 

 page 47 of the Bulletin will show the number and names of the 

 several varieties under cultivation, and I now propose to place 

 these names in proper sequence. As was expected, many of 

 those recorded are merely synonyms, although in more than one 

 instance the names cover varieties which have probably been obtained, 

 1st, by the conscious or unconscious selection practised by the culti- 

 vator, or 2ndly, by the influence of the climate and seasons of the 

 countries in which they have been grown. 



There are doubtless several other species of Dioscorea grown in 

 various West Indian islands, but the list here given includes those 

 which are most important as food producers for the people. The 

 " Kew Index" under the head of Dioscorea give some 300 names, and 

 this of itself will afford some idea of the number of species. 



It is not proposed, however, to enter into a discussion of the 

 various species and their differences, but simply to refer them with a 

 few notes as to their proper affinity to the names given by Botanical 

 authorities. 



Dr. Nicholls in Tropical Agriculture refers to four species : Dios- 

 corea alata, D. sativa, D. acnleata, and D. triphi/lla. Baron Von 

 Mueller in Tropical Plants enumerates twenty species, but his 

 description of the roots of plants under the names given by Nicholls, 

 shew that these authors had certainly different plants in view. 



Grisebach in the Flora of the West Indies enumerates nine species, 

 and among these he placed the Linnean — D. sativa under the D. lutea, 

 of Mey ! which shows that the nomenclature of the Dioscoreas must 

 be admitted to be anything but clear. This no doubt arises from the 

 fact that the parts of the plants required for determination are very 

 difficult to procure, for plants may be well grown for years without 

 furnishing them, and yet be at the same time sufficiently vigorous to 

 ripen good crops of fine edible tubers. We have ourselves grown in 

 these gardens an experimental patch for several seasons, and as yet we 

 have no certain material for the identification of many varieties. 



