440 The Systematic Value of the New Species. 



important, distinctions are afforded by the degree of 

 hoariness and so forth. 



The following questions suggest themselves : Has 

 Oenothera biennis been through a period of mutation 

 similar to that through which O. Laniarckiana is going 

 now? If it has, did it give rise to species which now 

 exist in the same way as 0. Laniarckiana is doing now? 

 Have the existing forms arisen directly from it or do 

 they owe their origin to repeated mutations? Finally 

 does there exist anywhere at the present moment a mu- 

 table family of O. biennis which is perhaps giving off 

 some of the forms which we know and others, perhaps, 

 as well ? These and other questions must for the present 

 be set aside for future investigation to answer. 



At any rate they serve to illustrate the theme of the 

 present chapter, which is that the Onagra-group is pre- 

 cisely parallel to the group of mutations which is being 

 produced by 0. Laniarckiana. It is older and perhaps 

 more extensive. But if the distinctions between species 

 within the two groups can be shown to be of the same 

 systematic value, the parallel between my new species 

 and the older species of recognized position will strongly 

 be supported by pure systematic evidence. 



Now that I have foreshadowed' the contents of the 

 paragraphs that follow, let us go back to O. Laniarckiana.^ 



^ Oenothera grandiflora Ait. = 0. suaveolens Desf. is often con- 

 fused with Laniarckiana either under one of these names or as O. 

 macrantha Hort. The facts are as follows It was first described 

 by WiLLDENow in his Species Plantariim (Vol. II, 1799, p. 306) but 

 seems to have been figured before that time by L'Heritier, Stirpes 

 novae, Tom. II, Plate 4. De Candolle in his Prodromiis suggests 

 that O. grandiUora Ait. and O. suaveolens Desf. may perhaps be dif- 

 ferent species. Desfontaines who gives no description of it in his 

 Tableau (ist edition 1804, p. 169; 2d edition 1815, p. 195) seems to 

 regard the two names as synonyms. 



In the general Herbarium of the Museum of Natural History at 

 Paris I found in the drawer for O. biennis a sheet of paper on which 



