INTRODUCTION. 



3INCE a considerable part of the State of Ohio was once 

 covered by the continental glacier of the glacial epoch, the 

 present surface is in many places covered by a thick 

 deposit of drift. In the regions of terminal moraines and 

 moraines of recession, the surface is usually diversified by hills 

 and hollows with a comparatively new and irregular drainage 

 system. The depressions thus formed give rise to the numerous 

 swamps, ponds and lakelets, which constitute a very character- 

 istic feature of the landscape and have a very important bearing 

 on the plant distribution. 



Being interested in the plant geography and ecology of the 

 State, the authors proceeded to make a systematic study of one 

 of these glacial lakelets. Brush I^ake being favorably situated 

 was chosen for study and the work of observation and collecting 

 has been carried on for several years. To help defray necessary 

 expenses, several small grants were obtained form the McMillin 

 Fund of the Ohio State Academy of Science and we wish here to 

 express our thanks to the Academy for the assistance received. 

 Thanks are also due to Mr. C. F. Wheeler, of the United States 

 Department of Agriculture, for kindly determining the species of 

 Cyperaceae, and to Mr. Geo. Riddle, owner of the lake, for the 

 photograph of the lake taken in 1887. 



