INTRODUCTION 



A GROUPING of plants upon the natural basis of environ- 

 ment, including soil, shade, moisture, etc., has long seemed to 

 me possible. This book is the outcome of that thought. The 

 influence of surroundings is especially noticeable in the vege- 

 table world. A plant born to wet soil will not flourish in dry. 

 One adapted to open fields will not bury its seeds in the cool 

 mould of deep woods. Or if it survives a change of locality, 

 its type is changed, and in this way it is quite possible for 

 new varieties to arise. 



For this reason, if the soil be changed an army of new 

 seeds will spring up. Weeds follow the trail of the farmer's 

 plough. The felling of forest trees destroys shade-lovingplants, 

 giving room to those which prefer sunshine and drier ground. 

 Wherever a new road is introduced, certain wayside plants 

 will appear along the border. Some plants are called "fire- 

 weeds," from their tendency to cover burnt-over districts. 

 Whether the seeds of foreign plants lie always in the soil, 

 ■ responding to the touch of different conditions, has not been 

 satisfactorily determined. The " alternation of crops," which 

 farmers find so profitable to their soil and harvests, may have 

 its suggestive prototype in nature. 



On the other hand, there are some plants which, democratic 

 and Bohemian in their nature, refuse to be restricted, and 

 drop their seeds with equal success in sand or mould. Where 



