224 TROPICAL AGRICULTURE 



green brier which belongs to the same genus. The plants are 

 indigenous to the tropical regions from Mexico to Brazil. The 

 official drug sarsaparilla is the dried roots of the plant. These 

 roots contain about 2 per cent, of saponin, which is the active 

 principle. The American sarsaparilla is Aralia nudicatdis, 

 an entirely different and unrelated plant. 



SQUILL 



This drug is obtained from a plant ( Urginia scilla), native of 

 the Mediterranean country. At the base of the plant an onion- 

 like bulb is developed. The bulb scales are cut into sections 

 and dried in the sun or in desiccators by the use of artificial 

 heat. Squill has a diuretic and purgative action. 



SENNA 



The drug senna is obtained from small shrubs which are 

 native to Egypt and Arabia. Alexandrian senna is obtained 

 from Cassia acutifolia and Indian senna from C. augustifolia. 

 The leaves of all the common species of Cassia are pinnate and 

 the flowers yellow, resembling sweet pea flowers in shape. 

 Senna is quite extensively cultivated in India. The dried leaves 

 and the pods are used in medicine for their laxative properties. 

 Senna is also cultivated to some extent in the Desert of Sahara. 



Purging cassia (C. fistula), a native tree of India, is widely 

 cultivated throughout all tropical countries as an ornamental. 

 The tree reaches a height of 20 to 40 feet, has a smooth gray 

 bark, and handsome racemes of large pale yellow flowers. The 

 pods are J^ to i inch in diameter and often attain a length of 

 2^ feet. The supply of the drug from this plant comes chiefly 

 from Central America, South America, and India. The tree 

 begins bearing at the age of 4 years. The pulp in the pods 

 is a thick, brown, molasses-like substance with a heavy odor. 

 It contains 50 per cent, of sugar and also a laxative principle. 



