34 



MUTANTS AND HYBRIDS OF THE OENOTHERAS. 



The rosettes of 0. lamarckiana and 0. rubrinervis which failed to 

 send up flowering shoots in 1903 endured the following winter, which 

 was of maximum severity, and began growth in a normal manner in 

 the spring of 1904, but were uprooted to make room for a new series of 

 experiments. 



No actual difference has been found in the power of producing 

 pollen among the parent-form, the mutants grown in the New York 

 Botanical Garden, and the other American species. All produce an 

 abundant crop of pollen, and show many faulty grains. 0. rubrinervis 

 was found to produce a greater number of capsules, and the seeds ger- 

 minated more readily than those of the parent-form, the plants reaching 

 maturity earlier than 0. lamarckiana. 0. gigas, on the other hand, 

 grows more slowly than the parent-form, as stated above, although it 



Fig. 2. Seedlings of Onagra gigas, about five weeks old, showing variations 



in forms of leaves. 



produces seeds abundantly, which show a high percentage of germina- 

 tion. Both species are supposed by De Vries to be quite equal to the 

 parental type in vigor, or perhaps to excel it. The latter suggestion 

 is supported by the marked reproductive capacity of these forms in 

 hybridizations When crossed with the parental form or with other 

 mutants, the dominance of the characters of 0. gigas and O. rubri- 

 nervis is especially marked, most so in the case of 0. gigas. 



In continuation of the work carried on in previous cultures obser- 

 vations of 0. gigas were made for the purpose of placing on record an 

 exact description of its characteristics as grown in America. The 

 formal descriptions of the parental type andO. rubrinervis and 0. nanella 

 have already proved useful in the various phases of the present investi- 

 gation. (MacDougal, 1903.) 



