334 Interaction of Genes 



A "palm" is produced by Y, 0, and T acting together, and a 

 "fern-oak" {yyooTT) crossed with a "tongue" {YY 00 tt) 



Fig. 95. Leaf types in Primula resulting from gene interaction. Upper left, 

 fern-oak, y o T; upper right, fern, y O T; lower left, fern-oak-tongue, y o t; 

 lower right, a crimp tj^pe. (Photograph by Dr. W. Brooks Hamilton from 

 herbarium material furnished by Dr. Edgar Anderson.) 



would give a "palm" {Yy OoTt). The F2 phenotypic ratio 

 would be: 



27 "palm" —YOT 3 "fern-oak" —yoT 



9 "fern" —yOT 3 "fern-tongue" —ijOt 



9 "oak" —YoT 3 "oak-tongue" —Yot 



9 "tongue" — YOt 1 "fern-oak- tongue" — y o t 



Even this, however, does not explain the complete situation 

 in Primula sinensis. Other types are "maple," claw," and two 

 types with crimped leaves. Each crimped type is the result of 



