122 Select Plants for Industrial Culture 



Dioscorea nummularia, Lamarck. 



The Tivoli-Yam. Continental and insular India, also South-Sea 

 Islands. A high-climbing, prickly species, with opposite leaves. Roots 

 cylindrical, as thick as a man's arm ; their taste exceedingly good. 



Dioscorea oppositifolia, Linne. 



India and China. Not prickly. One of the edible yams. 

 Dioscorea pentaphylla, Linne". 



Continental and insular India, also South-Sea Islands. Likewise 

 a good yam. A prickly species, with alternate divided leaves. 



Dioscorea purpurea, Roxburgh. 



India. In Bengal considered next best to D. alata and D. globosa. 



Dioscorea quinqueloba, Thunberg. 



Japan, and there one of several yam-plants with edible tubers. 

 Among numerous congeners are mentioned as providing likewise root- 

 vegetables : D. piperifolia (Humboldt) from Quito, D. esurientum 

 (Fenzl) from Guatemala, D. tuberosa and D. conferta (Yellozo) from 

 South-Brazil, D. Cayennensis (Lamarck) from tropical South-America, 

 D. triphylla (Linne) from tropical Asia, D. deltoidea (Wallich) from 

 Nepal. Of these and many other species the relative quality of the 

 roots and their adaptability to field-cultivation, require to be more 

 fully ascertained. 



Dioscorea sativa, Linne". 



Southern Asia, east as far as Japan, also in the South Sea-Islands, 

 North- and tropical East- Australia, likewise recorded from tropical 

 Africa. Stem cylindrical, not prickly. The acrid root requires 

 soaking before boiling. The plant has proved hardy in the Southern 

 States of North-America. Starch is very profitably obtainable from 

 the tubers. 



Dioscorea spicata, Roth. 



India. Roots used like those of other species. 



Dioscorea tomentosa, Koenig. 



Ooyala-Yam. India. The nomenclature of some of the Asiatic 

 species requires further revision. 



Dioscorea trifida, Linne fil. 



Central America. One of the yams there cultivated. Various 

 other tuberous Dioscorese occur in tropical countries, but their respec- 

 tive degrees of hardiness, taste and yield are not recorded or 

 ascertained. The length of the warm season in many extra-tropical 

 countries is probably sufficient for ripening all these yams. 



Diospyros Ebenum, Koenig.* 



Ceylon, where it furnishes the best kind of Ebony-wood. It is not 

 uncommon up to an elevation of 5,000 feet in that island, according 

 to Dr. Thwaites; hence I would recommend this large and valuable 



