127 



generation consists of two spore-bearing phases, the attached 



sporogenous filaments of the cystocarp and the free tetrasporic 



plant, Dr. Fritsch accepts the view of Dr. I. F. Lewis that the 



first of these represents an intercalated antithetic phase, while 



the second represents a phase strictly homologous with the 



sexual plant. 



Marshall A. Howe 



Hybrid Origin of Oenotliera Lamarckiana* 



In this paper Davis reaches an approximate conclusion on the 

 old question as to whether Oenothera Lamarckiana is of hybrid 

 origin. The parents used were 0. franciscana from California 

 and 0. biennis from Holland, which he assumes may have met 

 in England, from where he believes de Vries's Lamarckiana came. 

 The form obtained resembles Lamarckiana rather closely, but 

 the assumption of the possibility of a cross between species 

 native to regions as far apart as California and Holland makes 

 the hybrid origin of Lamarckiana seem less convincing than if 

 the assumed parents were found growing in closer proximity. 



Davis calls his form 0. neo-Lamarckiana. It is now in the 

 fourth generation from the original cross and was derived from 

 a single plant selfed in the Fo. From the "most promising" F3, 

 549 offspring lived to be set out into the garden. Of these 198 

 resembled Lamarckiana de Vries, while the other 351 suggested 

 franciscana. The author recognizes some variation among the 

 neo-Lamarckiana plants, but he says "the best plants are so 

 close to the Lamarckiana of de Vries that I can only distinguish 

 them by small plus or minus expressions of a few characters." 

 Davis does not state whether all the observed variations of his 

 Oenothera fall within the range of variability for de Vries's 

 Lamarckiana. 



Davis tests the breeding behavior of 0. neo-Lamarckiana with 

 reference to the production of twin-hybrids and the throwing of 

 mutants, which are the most important characters of the true 

 Lamarckiana. He obtains twin-hybrids, but it is perhaps not 

 at all established that the twin-hybrids of de Vries or Davis are 



* Davis, B. M. Oenothera Neo-Lamarckiana, Hybrid of O. Franciscana 

 Bartlett X 0. Biennis Linnaeus. Am. Naturalist 50, 688-696, 1916. 



