in Extra-Tropical Countries. 121 



the finest esculent roots of the globe. A variety of a bluish hue, culti- 

 vated in Central America (for instance at Caracas), is of very delicious 

 taste. 



Dioscorea alata, Linn.* 



The Uvi-Yam. India and South- Sea Islands. The stems are 

 four-angled and not prickly. The tubers, of which there are many 

 varieties, will attain under favorable circumstances a length of 8 feet, 

 and the prodigious weight of 100 pounds. This species and the pre- 

 ceding are the two principal kinds cultivated in tropical countries. 

 D. alata is in culture supported by reeds. It is propagated from 

 pieces of the old root, and in warm climes comes to perfection in about 

 seven months. The tubers may be baked or boiled. It is this 

 species, which has been successfully cultivated in New Zealand and 

 also in the Southern States of North- America. 



Dioscorea glabra, Roxburgh.* (Z>. Batatas, Decaisne.) 



The Chinese Yam. From India to China. Not prickly. The 

 root is known to attain a length of 4 feet, with a circumference of 

 14 inches, and a weight of about 14 Ibs. The inner portion of the 

 tuber is of snowy whiteness, of a flaky consistence and of a delicious 

 flavor; preferred by many to potatoes, and obtainable in climes too 

 hot for potato-crops. The bulblets from the axils of the leaf -stalks, 

 as in other Dioscoreas, serve as sets for planting, but the tubers from 

 them attain full size only in the second year. The upper end of the 

 tubers offers ready sets, but there are dormant eyes on any portion of 

 the surface of the tubers (Sir Samuel Wilson, General Noble). First 

 grown in Australia by the author in 1858. A remarkably hardy 

 species ; its yam-root keeps well (Vilmorin). 



Dioscorea globosa, Roxburgh. 



India. Roxburgh states this to be the most esteemed yam in 

 Bengal. 



Dioscorea hastifolia, Nees. 



Extra-tropical Western Australia, as far south as 32. It is evi- 

 dently one of the hardiest of the yams, and on that account deserves 

 particularly to be drawn into culture. The tubers are largely con- 

 sumed by the local aborigines for food. This the only plant, on which 

 they bestow any kind of cultivation, crude as it is. Fit for arid 

 situations, but fond of lime. 



Dioscorea Japonica, Thunberg. 



The hardy Japan- Yam. Not prickly. The material here for 

 comparison is not complete, but seems to indicate, that D. transversa 

 and D. punctata (R. Br.) are both referable to D. Japonica. If this 

 assumption should prove correct, then we have this yam along the 

 coast-tracts of North- and East- Australia, as far south as latitude 

 33. In Australia we find the wild root of good taste and large size; 

 the tubers are eaten by the savages raw when young, roasted when 

 aged (E. Palmer). 



I 2 



