Varietäten, Descendenz, Hybriden. 581 



herbarium specimens, make it probable that the "European bietinis'^ 

 so-called, rather than 0. Lamarckiana, was the first Oenothera in- 

 troduced into Europe. Herbarium specimens show, however, that 

 forms closely resembling if not identical with O. Lamarckiana and 

 O. rubrinervis, formerly occurred wild in the western region of 

 Colorado and New Mexico, and that other forms which, from 

 their flower characters, must be closely related to O. Lamarckiana 

 also occur there even now. 



Granting that O. Lamarckiana must have undergone crossing 

 in its ancestry, it does not necessarily follow that it has been syn- 

 thesized by a Single cross, such as O. grandißora X ö- biennis. The 

 fact that the characters of the parents are usually blended in crosses 

 between Linnaean species o{ Oenothera, while O. Lamarckiana agrees 

 with O. biennis in certain bud characters and with 0. grandiflora 

 in certain other flower characters, does not favor the hypothesis 

 that 0. Lamarckiana originated from this cross; and the evidence 

 offered by Davis is not supported by a sufificiently critical study 

 of the characters of the three species concerned, the flowers of his 

 hybrids being little more than half the size of ordinary O. Lamarckiana 

 flowers. By selecting certain other races of 0. biennis for crossing 

 with O. grandiflora, hybrids more closely resembling O. Lamarckiana, 

 at least in foliage, could doubtless be obtained. It would appear 

 that, as far as the characters are concerned, the "European bie^inis''' 

 is as likely to have originated by a cross between O. biennis and 

 0. Lamarckiana , as 0. Lamarckiana is to have originated from O. 

 grandiflora X O- biennis. 



From the evolutionary Standpoint, however, the important 

 question is not whether a given "species" has arisen through cros- 

 sing, because this is the condition under which the evolution ot 

 open-pollinated species must have taken place. Whether or not we 

 assume that mutation is the result of previous crossing, it is neces- 

 sary to determine whether the new types which appear are pro- 

 gressive and will form races which will become in turn to proge- 

 nitors of future types. 



Even if it be assumed that O. Lainarckiana originated from a 

 cross between 0. grandiflora and O. biennis, such crosses must 

 have occurred in nature in North America centuries before the 

 advent of the white man. For there is ample evidence that both 

 these species originally occupied the Virginia-Carolina region. 



The natural and necessary tendency of systematists and col- 

 lectors is to abstract a few from many existent types, as the foun- 

 dation for their species. The result is that the actual limits between 

 Linnaean species appear well-defined until the discovery of inter- 

 mediate races bridging such gaps makes it appear that, in many 

 cases at least, the lines drawn between Linnaean "species" are 

 purely arbitrary. This is shown by cultures of many races belonging 

 to O. biennis L, and 0. miiricata L. from various parts of North 

 America. 



One piece of negative evidence which does not favor the hypo- 

 thesis that O. Lamarckiana originated from O. grandiflora X 0. 

 bien}iis, is the fact that none of the mutants from O. Lamarckiana 

 have hitherto shown any tendency to revert to either of the puta- 

 tive parents, but rather, all seem to agree with O. Lamarckiana in 

 a certain constellation of flower characters. From plants from garden 

 seeds, however, which have evidently undergone crossing (e. g.. O. 

 suaveolens from the Nantes Botanical Garden), the author has 



