Naturalisation in Extra-Tropical Countries. 153 



for. The fresh dust-like spores should be scattered through moist 

 forest-valleys, to ensure new supplies of these superb forms of 

 vegetation for the next century. D. Billardierii is nowhere 

 antarctic. Frond-fragments, as not quickly shrivelling, in ex- 

 tensive demand for marketable table-bouquets. 



Digitalis purpurea, Dodoens. 



The Foxglove. Western Europe. A biennial and exceedingly 

 beautiful herb of great medicinal value, easily raised. In Norway 

 it grows to lat. 63 52' [Schuebeler] . Chemical principles : digitalin, 

 digitaletin and three peculiar acids [Wittstein.] Bees must be 

 kept away from this plant. 



Dimoehloa Andamanica, Kurz. 



Andamans. A scandent Bamboo, rising to fully 100 feet. Should 

 be of particular value for scenic culture. D. Tjankorreh (Buese) 

 extends from Java to the Philippines, ascends to 4,000 feet eleva- 

 tion, but is not so tall as the other species. 



Dioscorea aculeata, Linne.* 



The Kaawi-Yam. India, South- Sea Islands. Stem prickly, as 

 the name implies, not angular. Leaves alternate, undivided. It 

 ripens later than the following species, and requires no reeds for 

 staking. It is propagated from small tubers. This yam is of a 

 sweetish taste, and the late Dr. Seemann regarded it as one of the 

 finest esculent roots of the globe. Will keep for nearly a year ; 

 weight to 8 Ibs. A variety of a bluish hue, cultivated in Central 

 America (for instance at Caraccas), is of very delicious taste. The 

 fresh tubers contain about 15 per cent, starch [Dr. Th. Peckolt.] 



Dioscorea alata, Linne.* 



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 preceding are the two principal kinds cultivated in tropical 

 countries. D. alata is in culture supported by reeds. It is pro- 

 pagated 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. 

 A variety or allied species with branched tubers is mentioned by 

 Peckolt as Angola- Yam, containing about 24 per cent, starch. It 

 may be only cultivated perhaps in Africa. 



X 



Dioscorea atropurpurea, Koxburgh. 



Southern India. Root elongated, attaining a weight of 2 Ibs., of 

 very nice taste. Starch about 18 per cent. [Peckolt], sugar 7 per 

 cent. ; thus richer in sugar than any other species. 



