INTRODUCTION. 
INCE 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. ‘he 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 Lake 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. 
