89 



gkuKoLis; their wings are broader than the half of a circle, so tliat 

 the apex of the capsule is cordate : at the base the wing passes by 

 a well marked angle into a wing on the stalk. 



This species of Dioscorea was received in the Botanic Gardens, 

 Singapore, from the Gold Coast and from Southern Nigeria in 

 February and July, 1915, through tlie Eoyal Gardens, Kew. The 

 first Singapore crops were dug in November, 1915 and February, 

 1916; the second in December, 1916 and the third in December, 

 1917. I^'rom the small beginnings of the first crop the stock has 

 been built up sufficiently to justify a record of the returns got at 

 tlie third crop. These were: — 



Gardens' number number of average yield per 



aiul name of race. 



^ ., .^Ist bed 

 330 Eyiben^.^,j,| ,^^,^^ 



336 Twayo o lorum 



328 Fsinrinmin 



316 Puna 



340 Oparaga 



322 Odee krukupa 



324 Batafu entumtu 



334 Efura 



310 Bayere pa 



•■)76 Eururuka ai)inia 



2. The Yellow or Twelve Months Guinea Yam. 



Tbe ii|)]X'r block of plate vii. represents a race of another 

 species of Pio.scorea — that which is second in importance upon the 

 Guinea coast. It is believed that it is Dioscorea cayenensis, Lamk. 

 Apparently the Portuguese early took it to the New World: and 

 when it fell into the hands of the French botanist Lamarck, he in 

 ignoTanee of its African origin named it from the colony whence 

 his specimens came. It is a pity that it should have so obtained a 

 misleading specific name. The identity of D. cai/enensis with D. 

 prehensilis which Bentham described when working at the collections 

 made on the Niger Expedition, has recently been declared by 

 French botanists (vide Chevalier et Perrot, Les Vegetaux utiles de 

 I'Afrique tropicale frangaise, viii, Paris, 1913, p, 356 and Jumelle, 

 Les cultures coloniales, Legumes et Fruits, Paris, 1913, p. 12). 



As the plate shows, the tubers of D. cayenensis are unlike those 

 of the White Guinea yam in being more irregular and with a thick 

 neck, and somewhat uneven surface. They differ also in being 

 yellow fleshed. 



The new shoots are thick and very prickly with dark reflexed 

 prickles : they are of a purplish green, and carry alternate leaves at 

 first, which may have thick branches in their axils in positions such 

 as to prevent the stem from slipping back among the vegetation into 

 which it is climbing. 



The leaves are quite unlike those of the White Y"am in their 

 flatness in life and greater breadth. They are equally dark green. 



