360 BOTANICAL GAZETTE [may 



was in the same condition of mutability at the time of its first 

 appearance as it is now, is of course a different question.'^ 



Summing up the results of this historical investigation, we may 

 say: 



1. Oenothera Lamarckiana Ser. is represented by specimens in 

 the herbaria of Lamarck, Pourket, and Michaux (pis. XVII- 

 XIX), and is, so far as this material enables us to judge, at the 

 present time exactly the same plant as it was at that period. It 

 has come down to us, through more than a century, as unaltered 

 and as constant as true species usually do. 



2. It has been a component of the flora of the eastern United 

 States, where Michaxjx collected it and whence Lamarck derived 

 his specimen. 



3. At the present time it is a component of the flora of England, 

 and is as well established in that country as is 0. biennis in different 

 parts of Europe. 



4. The strain which is now in cultivation, and which was intro- 

 duced into the trade about the middle of the last century, was 

 probably derived from some wild Enghsh locality, which itself 

 may have come from an introduction into Europe of the seeds 

 coUected either by Michaxjx himself or by some other botanist of 

 his period. 



Amsterdam 



EXPLANATION OF PLATES XVII-XIK 



Plate XVII 



Oenothera grandiflora Lam. (O. Lamarckiana Ser.) : the authentic specimen 

 in the herbarium of Lamarck, two-thirds natural size, referred to as .4 in the 

 text; in the left upper comer a bunch of flower buds of my culture of 1913, 

 dried and pressed, is given for comparison, and photographed together with 

 the main specimen. 



Plate XVIII 



Oenothera grandiflora Lam. (O. Lamarckiana Ser.): the specimen in the 

 herbarium of Father Pourket, one-third natural size; on the label is written 

 Onagra mdgaris grandiflora Spach. 



s tJber die Dauer der Mutationsperiode bei Oenothera Lamarckiana. Ber. 

 Deutsch. Bot. Gesells. 23:382. 1905. 



