VOLUME LXIII 



NUMBER I 



THE 



Botanical 



Gazette 



JANUARY ran 



OENOTHERA LAMARCKIANA MUT. VELUTINA 



Hugo DeVries 



(with plate i) 



One of the rarest mutations of Oenothera Lamarckiana is that 



changed 



hybrids 



more 



striking because in hybrid combinations these twins ap 

 and, as it seems, easily. But in the same way many o 

 tions, which apparently might reasonably be expected 



muta 



must 



may 



very rare. Why some mutations are common and others r; 

 still an open question. 



From the behavior of the twin hybrids in crosses we 

 deduce that the mutant velutina must be in the main recessive to 

 the parent species, and that the mutant laeta should be dominant 

 over the velutina. If there were but one character involved, this 

 would mean that the mutant laeta must be externally like O. La- 

 marckiana, and the same conclusion would have to be admitted 

 if there were more characters indissolubly bound together. This 

 being granted, the laeta could, of course, never be expected to 

 appear as a mutant. 



For some years, however, my cultures tend to show that the 

 mutations observed in the group of the Oenotheras are far more 

 compound phenomena than I was formerly inclined to assume. 

 This also seems to be the case with the splittings which so often 



1 De Vries, Hugo, On twin hybrids. Bot. Gaz. 44:401-407. 1907. 





