ABNORMALITIES IN OENOTHERA. 



BY R. R. GATES. 



In connection with my Oenothera cultures, particularly 

 among plants grown during the past two seasons at the 

 Missouri Botanical Garden, I have had occasion to observe 

 several interesting "abnormalities" of structure. These 

 include virescence or frondescence and polymery of the 

 flowers, tricotyly and variegation of leaves. I have thought 

 it wor|;h while to devote a short paper to a description of 

 some of these cases which have an evident bearing on 

 problems of variation and inheritance. 



Virescence. — In my experimental garden of 1909 four 

 plants exhibited virescence of the flowers. These were all 

 descendants in the second generation from plants which 

 were derived from the English coast near Liverpool, the 

 first generation having been grown at Woods Hole, except 

 in the case of one (No. 47), which was grown in the tropical 

 greenhouse at the University of Chicago. These four plants 

 were therefore all from cultures of closely related forms, 

 and in some of their characters were intermediates between 

 0. grandiflora and 0. Lamarckiana. The summer tempera- 

 ture at St. Louis in 1909 ranged exceptionally high, read- 

 ing 100° F. in the shade in one instance. The change in 

 climate which the plants experienced was therefore very con- 

 siderable, and one of the cultures had been subjected to such 

 high temperatures for two successive seasons. This may per- 

 haps have had something to do with the appearance of these 

 cases of virescence, the alteration in the conditions acting as 

 a stimulus to the production of the abnormality. That the 

 tendency to produce virescent individuals is inherited, is 

 shown by the reappearance of virescent plants in one race 

 in successive generations, and their failure to appear in 

 many other races, e. g., 0. Lamarckiana and its mutants. 



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