IMtW YORK 



BOTANtCAL 



OAKOEN 



THE 



GARDENS' BULLETIIN, 



5TRAIT5 5ETTLEnEINT5. 



\pl. II. Issued Augnst I2th 1918 No. 2 



A REPORT UPON THE EXPERIMENTAL CULTI- 

 VATION OF THE GREATER YAM-DIOSCOREA 

 ALATA— IN 1917. 



This is the third of a series of re))orts upon the cultivation of 

 the (Jreater Yam in the hardens, Singapore. The first was ])rinted 

 in this Bidleiin, vol. I., Xo. 9, pp. 397-304, and in it outline 

 camera lucida drawings of sixteen races were given. The second 

 report was printed in Vol. I., double Xo. 11-13, pp. 3Tl-39(), with 

 illustrations from photograplis of fifteen races upon six plates. In 

 this report fourteen races arc illustrated u])on four plates, Xo. T(i 

 appearing upon two of tliem. Besides tlicse tliree reports, there is 

 another in the Philippine Agriculturist and Forester, Vol. III., 

 X915, PI). 205-209, with illustrations of seven races. When the first 

 report in the Gardens' Bullelin and that in the Philippine Agricul- 

 turist and Forester were published, the numbering. system of the 

 Gardens had not l)een made consistent, and was not referred to : 

 therefore it is now convenient to draiw into one list the races 

 already illustrated, — being in all thirty-eight. This list is printed 

 as an aitpendix on pp. 43-14. 



The plates with this report show successively various morpho- 

 logical features not brought out l)efore. All the figures are on the 

 same scale, which is indicated by a half-metre measure in each 

 block. The upper block of the first ]:»late shows what variation may 

 be found in sister plants; it re])resents five tubers of an African 

 race called on the Gold Coast Eururuka nkakyi, and in Singapore 

 grown under the number 193, together with four tubers of a race 

 from Manila grown under the number 33. The African race pro- 

 duced tubers varying greatly in relative length, and in branching 

 and in l)eing sometimes flattened and sometimes round in transverse 

 section : the Manila race varied in its tubers being sometimes flat- 

 tened and sometimes round. It is necessary to ascertain the 

 "why" of this, if the classification is to he perfected; and atten- 

 tion is directed to it accordingly. The lower block of plate i, ex- 

 hibits four tubers of a race from Manila jirown under number 7G, 



