150 Trans. Acad. Sci. of St. Louis. 



EXPLANATION OF ILLUSTRATIONS. 



PLATES X-XI. 



PI. X. — Upper figure. A group of horn beam trees (Carpi7ius betulus) 

 in the arboretum of the Missouri Botanical Garden on the morning of Feb. 

 28, 1900. — Lower figure. The same group of trees on the morning of March 6, 

 1900. Note that one branch has been broken. 



PI. XI. — Upper figure. View looking east on Flora avenue, St. Louis, on 

 the morning of Feb. 28th, 1900. The tree in the foreground is a soft 

 maple {Acer dasycarpum) , likewise the row of trees of which it is one. The 

 trees at the left are birches (Betula alba). — Lower figure. The same street 

 (from the same spot) just a week later, March 6, 1900. Note that the maples 

 have not quite returned to their original position, while the birchen have. 



Issued April 12,1900. 



