Rbodora 
JOURNAL OF 
THE NEW ENGLAND BOTANICAL CLUB 
Vol. 15. March, 1913. No. 171. 
A NEW OENOTHERA. 
REGINALD RucGLES GATES. 
(Plates 100 and 101.) 
My cultures of Oenothera from seeds collected wild in various parts 
of the North American continent, have yielded a bewildering profusion 
of forms, races related to O. biennis L. and O. muricata L. being 
especially numerous. As is always the case when the number of forms 
under observation begins to be multiplied, the older lines of distinc- 
tion between "species" break down, and it becomes finally an arbi- 
trary matter, decided by convenience, where the line between two 
formerly distinct Linnaean species is to be drawn. Thus the multipli- 
cation of forms belonging to the two species mentioned above has 
necessitated drawing a more or less arbitrary line between them, as 
I have explained elsewhere,! and ranking all races on one side of this 
line with the O. biennis series, and all on the other side with the O. 
muricata series. Such a decision is of course based on a single char- 
acter, because no two differential characters will hold for all the forms. 
concerned. 
I chose for this purpose the character of flower-size, and reckon 
all species of this group having petals 12-30 mm. in length, as belong- 
ing to O. biennis, and all having petals 9-15 mm. in length, with Q. 
muricata. Flower-size is the most convenient character on which to 
base distinctions, and the same treatment should therefore be applied 
to O. grandiflora Sol.,? O. Lamarckiana Ser., and other species of the 
1 Gates, R. R. " Mutation in Oenothera.” Amer. Nat. 45: 577-606, 1911. 
?I pointed out elsewhere (Amer. Nat. 45: 588. 1911) that Solander should be 
credited with this species. 
