FORESTRY OF WEST AFRICA. 433 



tubers are edible, and from them a starch is prepared 

 by the natives of the West Coast of Africa. — Kew 

 Museum. 



Distribution : Upper Guinea. 



DlOSCOREACE^. 



Yam {Dioscorea sativa, L.). — Climbing plant, ex- 

 tensively cultivated in Asia, Africa and America for 

 its tuberous root, which is flat and palmated, about a 

 foot in breadth, white, within, and externally of a 

 dark-brown colour, almost approaching to black : it 

 is nutritious, of a good flavour, and is eaten either 

 roasted or boiled as a substitute for bread, and 

 somewhat resembles the potato, but is of a closer 

 texture. — 'Vegetable Substances Used for the Food 

 of Man,' Lankester, p. 167. 



Distribution : Cultivated in Sierra Leone. 



White Bockra or Winged Yam {Dioscorea alata, L.). 

 — Square-stemmed climbing plant. The roots of 

 this species afford a much more delicate and agreeable 

 food than those of D. sativa, and on account of their 

 lightness and easy digestion are preferred to bread by 

 many of the inhabitants of the West Indies. There 

 are several varieties, distinguished principally by the 

 size and shape of the roots, all of which, if well dried 

 in the sun and covered with ashes or sand, or put 

 into casks, will keep well in a dry situation for 



2 F 



