Bulletin 



OK THE 



Illinois State Laboratory 



OF 



Natural History 



Urbana, Illinois, U. S. A. 



STEPHEN A. FORBES, Ph.D., LL,.D., 

 Director 



Vol. X. Skptember, 1913 Article I. 



AN ASSOCIATIONAL STUDY OF ILLINOIS SAND PRAIRIE 



BY 



Arthur G. Vestal, A. M. 



