Table 2. — Dioscorea rotundata and D. cayenensis characteristics 

 and rating system — Continued 



Number Characteristic observed Rating system Scale and extremes 



22 



Upward folding of leaf lobes 



Estimated visually ■ • 



1 = minimum, 5 = 





to form a cup. 





maximum. 



23 



Upward folding of leaf 



do 



Do. 





along main vein. 







24 



Downward arching of leaf 



do 



Do. 





along main vein. 







25 



Undulation of leaf margins • 



do 



Do. 



26 



Internode length of stem • • • 



. A large lower inter- 



Centimeters. 







node, measured. 





27 



Leaf blade length 



1 he length oi a 



Do. 







1 1 1 c 



large lower leaf 









blade, measured. 





28 



Leaf blade width 



. Ihe width 01 the 



Do. 







same leaf. 









measured. 





29 



Lobe length 



. Ine length oi the 



Do. 







lobes from petiole 









junction to tip. 









measured. 





30 



Petiole length 



. Ihe length of the 



Do. 







petiole, measured. 





31 



Internode length divided by 





Ratio near 1. 





blade length. 







32 



Blade width divided by 



do 



Do. 





blade length. 







33 



Lobe length divided by 



do 



Do. 





■UI-^J— 1 J_l 



blade length. 







34 



Petiole length divided by 





Do. 





blade length. 







35 



Field vigor of entire plant • • 



. Estimated visually • 



. 1 = weak, 5 = 









vigorous. 



36 



Intensity of virus symptoms 



do 



■ 0 = no symptoms, 









5 = maximum. 



37 



Density of foliage 



do 



1 = low density, 









open, 3 = high 









density. 



38 



Reclassification of leaf type • 



. Classified by a non- 



1 = deltoid. 







linear system. 



2 = shield. 



3 = almost 

 circular like 

 D. cayenensis, 



4 = intermedi- 

 ate to the two 

 species, 



5 = small ovate 

 typical of 



D. rotundata, 



6 = typical 

 ovate. 



12 



