284 



GENETICS IN RELATION TO AGRICULTURE 



character of (E. rubicalyx is conditioned by one or two specific factors. 

 This new form (see Fig. 118) was discovered by Gates in 1907, among a 

 population of over 100 rubrinervis plants grown from self-fertilized seed 

 of rubrinervis. The original rubricalyx plant when self-fertilized produced 

 12 plants, 11 rubricalyx and 1 rubrinervis, which would indicate that the 

 original rubricalyx plant was heterozygous for one or more factors for 

 excessive production of anthocyanin and that rubricalyx is dominant to 

 rubrinervis. Gates has raised ten generations of rubrinervis (more than 



Fio. 118. Flower bud and leaf of A, (Enothera rubrinervis; B, (E. rubricalyx. The 

 deeper pigmentation of rubricalyx is not confined to the bud and lower side of the leaves, 

 but is also present in the stems. The rosette leaves also show more or less color on the 

 midrib in rubricalyx. 



one pedigreed strain) and found it to breed true and he has one strain of 

 rubricalyx that has bred true for five years, but as yet there are no data 

 on the results of a cross between them where the F 2 progeny were grown 

 on a large scale and with controlled seed germination. However, in Fi 

 rubricalyx is dominant. Another QEnothera character which is inherited 

 in simple Mendelian fashion is the typical feature of brevistylis (Fig. 115). 

 Brevistylis is known to breed true when self-fertilized and the results 

 of various crosses indicate that the short style is conditioned by a single 

 factor, although it is not always completely recessive in F\. Thus we 

 find that, while most of the experimental breeding data on oenotheras 

 cannot be interpreted in terms of ordinary Mendelian concepts, neverthe- 



