the Jamaican variety was distinct from any of the varieties from 

 Trinidad. 



Two botanical varieties have been distinguished. The variety 

 tuberosa is the most favored because of its flattened, horsehoof, 

 spheroidal to ellipsoidal tubers. These are always white in the West 

 Indies, but may be purple in the Guyanas. Varieties include Tatte 

 a Cheval', TRAT 50', and 'Mapuey Largo'. The variety 'Genuina' 

 includes the club-shaped and elongated, tubered types such as 

 'Cousse-Couche Violette', 'Cousse-Couche Rouge', and 'IRAT 24'. 



At the INRA station in Guadeloupe a collection of 50 clones is 

 maintained, including 22 from the West Indies, 18 from the 

 Guyanas, and 10 developed locally (9). This collection is the most 

 extensive ever developed of the species and marks Guadeloupe as 

 the principal center of study and development. Some features of 

 the collection are described below. 



Among the varieties, the annual growth cycle lasts from 300 

 to 340 days, and flowering from 130 to 250 days. Female clones 

 usually flower later and for a longer period than do male clones. 

 There are more female than male clones in the collection. 



Among leaf and stem characteristics, anthocyanin distribution 

 and intensity are the best qualitative traits for distinguishing va- 

 rieties. Presence or absence is noted on the upper and lower parts 

 of the petiole, on the petiole wings and main body of the petiole, 

 and on the wings of the stem and the interwing region. The in- 

 tensity of the anthocyanin coloration varies from pink or light 

 brown (caused by a mixture of anthocyanin and chlorophyll) to 

 dark wine purple. Tuber skin or flesh color is not necessarily 

 related to foliage color. 



Important underground characteristics distinguish varieties. 

 The diameter of the cluster in the soil varies from 20 to 80 centi- 

 meters. Actually, two modes occur: 40 to 50 centimeters and 70 to 

 80 centimeters. The fraction of the stolon that is not tuberized 

 varies from less than one-fourth to more than three-fourths of the 

 total length. Two modes are also observed with respect to this 

 characteristic. 



With respect to tubers, phelloderm and flesh colors are easy 

 to judge and are useful in distinguishing varieties. Shape is harder 

 to judge but includes at least two components, length and club 

 shape (enlargement of the terminal extreme) . About 84 percent of 

 the varieties show at least some terminal enlargement, although 

 in only 54 percent can the tuber be said to be club shaped. 



Yields are varietal traits but are discussed in a later section. 



Virus disease is an important factor limiting D. trifida growth 

 and production. So far, no clear-cut resistance has been shown. 

 Seedlings showing viral symptoms and yielding well have also been 



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