THE ECOLOGICAL DISTRIBUTION OF IOWA GRASSES. 



BY L. H. PAMMEL. 



CONTENTS. 

 General Discussion, 



Drainage of Iowa 379 



General Topography 382 



Altitude 382 



Temperature Data 386 



Classification of Life Zones 388 



Ecological Distribution. 



Xerophytic 391 



Halophytic 393 



Mesophytic , 393 



Hydrophytic 395 



