Plate XVI. 



Fig-. 1. Bur oak association, Winiiebagro area. A'li/'i/s sp. in the fore^rround, at llie left": 

 Pteris aqiiiliiia conspicuons under ihe trees. 



l.i&kj^'TS'^^ "• 



Fig-. 2. Black oak association, Oquawka area. A iew young Yines oi Psedera 2.iid dlasinis 

 have appeared, indicating the beginning of the succession to the mixed forest. 



