premature harvest practiced with D. rotundata is seldom used with 

 these species. 



D. transversa is known in New Caledonia (i ) for its ability to regrow 

 when harvested during the season, and this capability has been con- 

 firmed in Guadeloupe. Its ability to remain safely in the soil without 

 damage over a long time is expressed by the New Caledonian name, 

 wael, a term meaning partly "does not know the season." 



In Puerto Rico, individual plant yields have been recorded: 0.205 to 

 3.085 kilograms for D. hispida, 0.610 to 3.775 kilograms for D. pen- 

 taphylla, and 0.340 to 4.310 kilograms for D. dimietorum. The yields are 

 satisfactory for any Dioscorea species. In the wild, D. dumetorum has 

 been found with as high as 17 kilograms of tubers for a plant {13). D. 

 hispida reaches 50 kilograms (3). In Guadeloupe, D. pentaphylla 

 'WanyaF has yielded large tubers of 7 kilograms. D. transversa tubers 

 have varied from 600 to 4,000 grams per plant, as good as yields of D. 

 alata. Similarly, D. dumetorum has yielded more thanZ). cayenensis. 



DETOXIFICATION 



The best accounts of detoxification of D. h ispida are given by Ochse 

 and van den Brink (15). One method is to cut the tubers in pieces, cover 

 the surface with wood ashes for 24 hours, and then steep them in 

 seawater for several days. The pieces are then washed with freshwater 

 and dried. The process is repeated several times, and the pieces are not 

 eaten until dogs can eat them without noticeable ill effects. Another 

 technique is to dry the slices first, mixed with ashes. In the Philippines, 

 the producted "nambi" is formed by salting the tuber pieces and then 

 pressing them under water until no whitish sap remains. There are 

 many variations, but in every case the process is long and hard. 



Coursey (9) summarizes techniques for detoxification of yams. D. 

 dumetonim is always soaked in water in one way or another and is 

 often cut up or macerated before soaking. Extraction, at least in the 

 latter case, depends on the solubility of the poison in water. 



After yams are detoxified, they are almost always tested with 

 domestic animals before being used as human food. 



CULINARY CHARACTERISTICS 



D. dumetorum is the most unusual of the yams with respect to its 

 cooking characteristics. The yam is soft and succulent at harvest and is 

 easily bruised. A few days after harvest it begins to harden. Tubers 

 harvested only 1 week before cooking were hard, difficult to peel, and 

 required several hours of cooking. Even then they were hard and in 

 some cases not attractive to eat. Therefore, D. dumetorum tubers are 

 often sold precooked in West Africa. 



D. nuynmularia and D. peyitaphylla yam varieties differ in culinary 



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