Rhodora 
JOURNAL OF 
THE NEW ENGLAND BOTANICAL CLUB 
Vol. 13. October, 1911. No. 154. 
SYSTEMATIC STUDIES ON OENOTHERA,— I. 
OENOTHERA TRACYI, SP. NOV. 
HARLEY Harris BARTLETT. 
(Plate 93.) 
AN adequate systematic treatment of Onagra, the subgenus of 
Oenothera typified by Oenothera biennis, is greatly needed by students 
of heredity, who have been led by the work of de Vries to choose 
material for investigation from this complex and little understood 
group. On account of the fact that the species can not be correctly 
interpreted without studying living plants, it is not likely that such 
a treatment will be soon available. Miss Vail, however, has made a 
beginning in the careful definition of wild forms tested for constancy 
by cultivation under controlled conditions. The writer is carrying 
on a series of cultures at Bethesda, Md., for the purpose of continuing 
this line of work, and will publish the results as fast as practicable in 
order to make them available to other students. It is hoped that the 
work may culminate in a much needed revision. 
The desirability of determining the geographic ranges of the allies 
of Oenothera biennis should commend these plants to the attention 
of collectors. Specimens of the evening-primroses are at best far 
less satisfactory than most herbarium material, and should therefore 
be prepared with especial care. They should show all parts of the 
plant, even if several sheets are required to represent one individual. 
It is especially desirable to obtain seeds, so that rosettes, or even a 
second generation of mature plants, may be grown if needed. Our 
public herbaria do not contain a tithe of the material which a student 
of the evening-primroses would wish to see before attempting a 
revision, and many of the available specimens are very poor in quality. 
