162 TROPICAL AGRICULTURE 



largest supply is received from St. Vincent, Barbados, and 

 Ceylon. Arrowroot starch is considered to be very easily di- 

 gested and is generally recommended for invalids who have 

 found difficulty in digesting the starch from potatoes and other 

 plants. 



Tacca (T. pinnatifida) is a stemless plant, native of Ceylon 

 and the Pacific Islands, bearing 3-parted leaves on petioles i to 

 3 feet long. A scape of small greenish flowers is developed 

 at maturity and potato-like tuberous roots which yield a starch 

 equal to arrowroot and called pia by the Polynesians. This 

 plant was formerly much cultivated in Hawaii. It is still 

 cultivated to a large extent in India, Africa, and in various 

 other tropical countries. The tubers are dug after the leaves 

 fall and are grated, washed, and dried much like sago and 

 cassava. The plant is propagated by the division of the roots 

 and is commonly planted in rows 3 feet apart and 18 inches 

 apart in the row. 



SWEET POTATOES 



Sweet potatoes grow everywhere throughout the Tropics 

 and subtropics. They occur in a great number of varieties 

 with white, yellow, and purple flowers, and with all shapes 

 and sizes of leaves and of tubers. The tubers vary in size 

 from a few ounces to several pounds and in color from pure 

 white to dark purple. The flesh of the tubers of some varie- 

 ties is also purple and in addition white-fleshed and yellow- 

 fleshed forms are abundant. The sweet potato escapes from 

 cultivation and grows almost as a weed in some tropical coun- 

 tries, as, for example, in Cuba. In the Tropics the sweet 

 potato is propagated chiefly by stem cuttings. The tubers 

 mature within 3 to 7 months after planting. The sweet potato 

 is an extremely important food product in all tropical coun- 

 tries since it may be obtained the year round and bears trans- 

 portation well. Sweet potatoes have been shipped from Hawaii 

 to the mainland during the off season, particularly May to 



