IN EXTRA-TROPICAL COUNTRIES. 101 



Australia as far south as latitude 33°. In Australia we find 

 the wild root of good taste. 



Dioscorea niunmnlaria, 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 an arm ; their taste ex- 

 ceedingly good. 



Dioscorea oppositifolia, Linne. 



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



Dioscorea pentaphylla, Linn^. 



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

 wise a good Yam, A prickly species, with alternate divided 

 leaves, 



Dioscorea purpurea, Roxburgh, 



India, In Bengal considered next best to D, alata. 



Dioscorea quinqueloba, Thunberg. 



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

 Among numerous congeners are mentioned as providing like- 

 wise root vegetables : D. piperifolia (Humboldt) from Quito, 

 D, estu:ientum (Fenzl) from Guatemala, D. tuberosa and 

 D. conferta (Vellozo) from South Brazil, D. Cayennnensis 

 (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 the degree of facility of their field cultivation, require to 

 be more ascertained. 



Dioscorea sativa, Linne, 



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

 and North and tropical East Australia, likewise recorded from 

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

 requires soaking before boiling. It has proved hardy in the 

 Southern States of North America. 



Dioscorea spicata, Roth, 



India. Root used like those of other species. 



Dioscorea tomentosa, Koenig. 



Ooyala. Yam, India. The nomenclature of some of the Asia- 

 tic species requires further revision. 



