156 SELECT PLANTS FOR INDUSTRIAL CULTURE 



weeks it yields a second crop, and under favourable circum- 

 stances 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 such an abundant produce. Bright sunshine favours the 

 development of the dye principle, but frequent rains cause a 

 more luxuriant growth (Hartwig) . 



Inula Helenium, Linne. 



The Elecampane. Middle and South Europe, Middle Asia 

 eastward to Japan. A perennial herb. The bitter and some- 

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

 properties, is used in medicine. It contains also the amyla- 

 ceous inulin and the crystalline helenin. With the Mullein 

 (Verbasum Thapsus), L., adaptable for scenic effects. 



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



The Sweet Potato. Tropical South America. First brought 

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

 southern part of Australia and for New Zealand. The tubers 

 afford a palatable food, more nutritious than ordinary potatoes. 

 Varieties with red, white, and yellow roots occur. Each tuber 

 weighs generally from 3 Ibs. to 5 Ibs., but may occasionally 

 attain to 56 Ibs. The yield is from 200 to 300 bushels from 

 an acre. 



Ipomcea Batatilla, G. Don. 



Cooler regions of Venezuela. The tubers serve as sweet pota- 

 toes. Similarly useful I. platanifolia, Roem. et Schult., 

 from Central America, and I. mammosa, Choisy, from 

 Amboina. 



Ipomcea Calobra, Hill and Mueller. 



Central Australia. The large roots a fair esculent. 



Ipomcea megapotamica, Choisy. 



South Brazil and Argentina. The root attains several pounds 

 weight, and serves as jalap. Propagation by pieces of the root 

 or from cuttings of the underground stem. 



Ipomoea paniculata, R. Brown. 



Almost a cosmopolitan plant on tropical coasts ; thus indi- 

 genous to North Australia and the warmer parts of East 

 Australia. The tubers of this species also are edible. If 

 hardy, the plant would deserve cultivation. 



