THE 



AMERICAN NATURALIST 



Vol. XLVII August, 1913 No. 560 



GENETICAL STUDIES ON (ENOTHERA. IV 



The Behavior of Hybrids between (Enothera biennis 

 and (E. grandiliora IS the Second and 

 Third Generations 1 



DR. BRADLEY MOORE DAVIS 



Those who have followed the reports of my genetical 

 studies on (Enothera (Davis, '10, '11 and '12a) must have 

 noted that I have obtained during the past four years a 

 series of hybrids from the cross grandiflora X biennis 

 with various points of strong resemblance to forms of 

 (Enothera Lamarckiana De Vries. I say forms of (E. 

 Lamarckiana because it is, I think, clear (Davis '12a. 

 p. 383) that this species has within itself a number of 

 biotypes which, although in most respects essentially 

 similar, differ from one another in the size of the petals, 

 in the height of the stigma relative to the tips of the 

 anthers, and, to a lesser degree, in some other charac- 

 ters. These biotypes may be segregated by critical se- 

 lection and cultivation through pure lines and I venture 

 to believe that the Lamarckiana of De Vries 's cultures 

 was less pure when he began his studies twenty-five years 

 ago than it is to-day. At the present time a very large- 

 flowered type (petals 4-4.5 cm. long) is generally thought 



Naturalists at its meeting^n Cleveland on January 2, 1913. 



449 



