Naturalisation in Extra-Tropical Countries. 239 



have been tested for pigment. Over 100 have already been 

 recorded from extra-tropical Southern Africa alone. An Indigof era 

 of Georgia, said to be wild, perhaps I. Anil, yields an excellent 

 product. The pigment in all instances is obtained by maceration 

 of the foliage, aeration of the liquid and inspissation of the 

 sediment. 



Indig-ofera arg-entea, Linne. (I. ccerulea, Eoxburgh). 



Tropical and extra-tropical Northern Africa, Arabia and perhaps 

 India. A shrub, several feet high, closely allied to I. Anil, and 

 likewise a good Indigo-plant. 



Xndigrofera tinctoria, 



Warmer parts of Asia, as far east as Japan ; recorded also from 

 tropical Africa and even Natal as wild. A shrubby plant, attain- 

 ing a height of 6 feet. Pods straight, cylindrical, many-seeded. 

 Extensively cultivated in warm zones for indigo, and probably 

 hardy in mild temperate regions. The plant is frequently sold 

 fresh by the grower to the factories. The indigo-plant requires a 

 rich friable soil, neither too moist nor too dry. The seeds are 

 sown in furrows about a foot apart, and in hot damp climes the 

 plant can be cut in about two months, as soon as it begins to 

 flower ; in six or eight weeks it yields a second crop, and under 

 favourable circumstances as many as four crops can be gathered in 

 a year. The plants have to be renewed every year, as the old ones 

 do not yield an abundant produce. Bright sunshine favors the 

 development of the dye-principle, but frequent rains cause a more 

 luxuriant growth [Hartwig]. In 1884 Great Britain imported 

 104,000 cwt. of indigo, valued at 2,484,000 ; in 1889 the import 

 there was 90,238 cwt., valued at 1,777,000. 



Znula Kelenium, Linne. 



The Elecampane. Middle and Southern Europe, Middle Asia 

 eastward to Japan. A perennial herb. The bitter and somewhat 

 aromatic root, for the sake of its stimulating and tonic properties, 

 used in medicine. It contains also the amylaceous inulin and the 

 crystalline helenin. With many other large herbs adaptable for 

 scenic effects. 



Zpomoea Batatas, Poiret.* (Batatas edulis, Choisy.) 



The Sweet Potato. Tropical South- America. First brought to 

 Europe from Brazil. It has proved well adapted also for the 

 southern part of Australia and for New Zealand. Thriving singu- 

 larly well even during seasons of drought in Central Australia ; 

 weight of tubers to 1 Ib. there not quite rare. [Rev. H. Kempe]. 

 The copious starch from the tuber forms a good substitute for 

 Arrow-root (or rather Aru-root). The tuberous roots afford a 

 palatable food, more nutritious than ordinary potatoes ; they can 



