19 



again in tiic latter part of April, 191 7, and the same characters 

 observed. On most branches the flowers were ordinary pistillate 

 ones, like those on other trees in the neighborhood. They had a 

 receptacle in the form of an oblique cup closely surrounding the 

 basal one half or two thirds of the ovary, the two stigmas were 



Fig. 4. Longitudinal sections of a normal pistillate and of a perfect_fiower of 

 Populus grandidenlala. 



so deeply cleft as to give the appearance of four stigmas. On 

 nearby staminate trees the flowers were normal— a shallow, 

 oblique cup or disk with ten or twelve stamens, except near the 

 tip of the catkins where the number of stamens was reduced to 

 three or four. On the tree in question the abnormal catkins were 



