GENETICAL STUDIES ON OENOTHERA. IV 



II 



DR. BRADLEY MOORE DAVIS 



3. Hybrids of grandiflora B X biennis D in the F 2 

 Generation 



In my last paper (Davis, '12a, pp. 392-406) there was 

 described an especially interesting F 1 generation, culture 

 11.35, of the cross grandiflora B X biennis D. The 

 biennis male parent of this cross (Davis, '12a, pp. 385- 

 389, Figs. 1-3) was of a race with the stem coloration 

 characteristic of Lamarekiana, i. e., the papillae or glands 

 at the base of long hairs were colored red on green por- 

 tions of the stem. The grandiflora female parent bears 

 the same type of papillae, but they follow the color of the 

 stem and therefore lack the red over green portions of 

 the stem. The biennis parent then presented a character, 

 the red coloration of the papillae, that might be expected 

 to be present or absent in the F x , and to present an alter- 

 native inheritance in the F 2 generation. 



It will be remembered that in the F l generation of this 

 cross, grandiflora B X biennis D, consisting of 180 plants, 

 two sharply contrasted classes appeared (Davis, '12a, p. 

 395). Class I was represented by 12 plants which had 

 the stem coloration of the biennis parent (red papillae on 

 green portions of the stem). Class II was represented 

 by 168 plants with the stem coloration of the grandiflora 

 parent (stems above clear green). Other peculiarities of 

 these classes are described in the paper cited above, but 

 we are concerned at this time chiefly with the behavior of 



