210 



DioscoREA sr, 



" Cut and throw away ;" this yam comes nearest to that described 

 by Grisebacli as Dioscorea hulhifera, L. It was received from Kew 

 some two years ago as " Otabeite Potatoe." It is known in the "West 

 Indies as Potatoe yam from the fact of its bearing large quantities of 

 bulbils on the stem of the plants. The stem is sub-cylindrical in 

 form and bears alternate cordate leaves. The tuber is globose or 

 spherical in form and is generally covered with a number of large 

 fleshy roots. Its Grenada name — " cut and throw away" — well indicates 

 its value when compared with the produce of D. saliva and D. alata. 

 The tubers, however, produce a large percentage of starch of fair 

 qu,ality. 



Dioscorea tripliylla, L., Dioscorea i^olijgonoides, H.B.K., and 

 Dioscorea Kegeliana, Grish., are species which grow in Trinidad, but 

 so far as our observation goes, are of little economic imjDortance. 



The varieties of Dioscorea alata or '' white yam" produce in 

 some seasons numerous bulbils, or aerial tubers, which are very useful 

 for propagating purposes, but in other seasons few or none are 

 produced. 



The local names for the various kinds are many, and well-mixed ; 

 and it would be imj)ossible, if indeed it were desirable, for any writer 

 to enumerate them all. 



It is mentioned by Dr. Watt, Eeporter on Economic Products for 

 the Government of India, that the word "yam" is probably derived 

 from French igname, and the Spanish and Portuguese inhame, of 

 which it is probably an Anglo-Saxon corruption. 



In a description written in 1888 Dr. "Watt enumerates twenty - 

 four (24) species cultivated in the East. Several of these can 

 without much doubt be identified with our cultivated West Indian 

 species and varieties, but it is quite possible that species exist there 

 which might be worth while to introdiice to the West, and steps are 

 being taken to procure some of these for trial. Dr. Watt records 

 that some of the West Indian kinds have been exported to the East 

 chiefly through the exertion of Mr. R. Mitchell, Emigration Agent 

 for British Guiana at Calcutta, and they appear to have been highly 

 valued. 



Cultivation. 



Our method of cultivation in the Royal Botanic Gardens is one 

 which is simple in the extreme, and has given excellent results. 



