No. 532] GENETIC AL STUDIES ON (ENOTHERA 203 



inspection. Besides the above I have selected and cul- 

 tivated from this material three strains (grandi flora A. 

 B, and D), which have been carried through a second gen- 

 eration represented by twenty-four mature plants. 



It became apparent, as my cultures progressed, that 

 the Oenothera grand ill <tra growing near Tensaw is far 

 from uniform in character. I have so far selected four 

 distinct types of plants, only one of which, however, has 

 been cultivated in later generations. The fact that the 

 stigma of grandiflora is generally well above the tips of 

 the anthers prevents pollination in the bud and in the 

 opening flower, and offers a very much greater oppor- 

 tunity for cross pollination than is possible in biennis. 

 This condition is probably responsible for the hetero- 

 geneity of the species. 



The type which I have under cultivation and which has 

 proved stable is characterized by a somewhat broader 

 leaf than is common to the species. From it have been 

 differentiated the following three strains (A, B, and D), 

 which have been used in the crosses with (Enothera 

 biennis. 



1. Strain D came directly from a wild plant. 



2. Strains A and B are the result of a cross between 

 B and a similar plant, F, in the garden at Woods Hole 

 in 1908. The cross was made to fix thoroughly the char- 

 acters of a broad leaf and red coloration of sepals pres- 

 ent in both parents. The two strains (A and B) are es- 

 sentially similar, differing chiefly in the degree of red 

 coloration present in the sepals, a character that is var- 

 iable and probably cannot be depended upon as a fixed 

 factor. As a matter of fact, strain D in a second genera- 

 tion has proved very uniform and it is not likely that I 

 shall make further use of strains A and B. All three 

 strains are representative of the larger proportion of 

 the plants of grandiflora that have passed under my ob- 

 servation, being, however, what a gardener would select 

 as luxuriant forms with broader and larger leaves than 

 the average. 



