288 TROPICAL AGRICULTURE CHAP. 



It has been calculated that an acre of land will yield four 

 or five tons of yams in the year, and it is said that the same 

 quantity of sweet potatoes may be taken as a catch crop off 

 Returns fa e ground, this brings the return up to nine tons that is 

 the yield of ordinary potatoes from an acre of good land in 

 England. But as yams and sweet potatoes contain more 

 nutriment matter than the common potato, the actual yield 

 of food is greater in the case of the tropical vegetables. 



THE SWEET POTATO. Ipomxa Batatas. 



Habitat THE origin of the plant producing the sweet potato is 



obscure, but it is thought by botanists to be a native of both 

 hemispheres. It formerly grew wild in the woods of the 

 Malayan Archipelago, and batatas, a Malayan word, is the 



History of name given to the potato in the far East. The tuberous 

 roots of the plant are said to have been first mentioned by 

 an author named Pigafetta, who visited Brazil in the year 

 1519, and found the potato in use among the Indians as an 

 article of food ; it is probable, therefore, that it is a native 

 of South America. Soon, afterwards, the plant was carried 

 to Spain, and it spread over Europe, and was introduced 

 into England long before the common potato which has 

 now taken its place. and also its name. Dr. Pavy says, " The 

 tubers were imported into England by way of Spain, and 

 sold as a delicacy before the potato was known, and it forms 

 the article referred to when the name is mentioned by 

 English writers previous to the middle of the seventeenth 



Wide dis- century." Sweet potatoes are now cultivated extensively in 



the Ut iant f a ^ ^ e warmer regions of the globe, and in some countries 

 they form a large part of the food of the people. The 

 starchy and sweet tubers have an agreeable taste, and they 

 contain more nutritious matters than the common potato 

 which is the staple food of the peasants of Ireland. 



