28 MUTATIONS, VARIATIONS, AND RELATIONSHIPS OF THE OENOTHERAS. 



Variation in hiid characters. — It is a well-known fact that floral characters 

 fluctuate less in response to change of environment than vegetative characters, 

 though I know of no exact studies showing to what extent this is true. The 

 comparatively larger flowers of alpine regions And an explanation on this 

 basis since the alpine plants have generally migrated from the lowlands. 

 I have seen a specimen of Lobelia syphilitica less than 8 cm. tall and dwarfed 



Fig. 7. — Correlation between width (subject) and length of leaf in OcjioZ/iera/amarcfctana. 

 Measurements in millimeters. Coefficient of correlation, . 8330 ± . 0058. 



Specimens of numerous other species bearing flowers almost as large as is 

 normal for the species. 



Having sufficiently demonstrated the unsatisfactory character of height, 

 branching, and leaf -form for statistical comparisons because of their great sen- 

 sitiveness to even shght changes in the environment, I have decided that in the 

 buds is to be found probably the most satisfactory material for a continuation 



