176 GEOLOGY OF EASTEEN WISCONSIN. 



CHAPTER III. 

 NATIVE YEGETATIOK 



The most reliable natural indications of the agricultural capabilities 

 of a district are to be found in its native vegetation. The natural 

 flora may be regarded as the result of nature's experiments in crop 

 raising through the thousands of years that have elapsed since the re- 

 gion became covered with vegetation. If we set aside the inherent 

 nature of the several plants, the native vegetation may be regarded as 

 the natural correlation of the combined agricultural influences of soil, 

 climate, topography, drainage and underlying formations and their 

 effect upon it. To determine the exact character of each of these 

 agencies independently is a work of no little difficulty; and then to 

 compare and combine their respective influences upon vegetation pre- 

 sents very great additional difficulty. But the experiments of nature 

 furnish us in the native flora a practical correlation of them. Tho 

 native vegetation therefore merits careful consideration, none the less 

 so because it is rapidly disappearing, and a record of it will be valua- 

 ble historically. 



It is rare in nature that a single plant occupies exclusively any con- 

 siderable territory, and in this respect there is an important difference 

 between nature's methods and those of man. The former raises mixed 

 crops, the latter chiefly simple ones. But in nature, the mingling of 

 plants is not miscellaneous or fortuitous. They are not indiscrimi- 

 nately intermixed with each other without regard to their fitness to be 

 companions, but occur in groups or communities, the members of which 

 are adapted to each other and to their common surroundings. It be- 

 comes then a question of much interest and of high practical import- 

 ance to ascertain, within the region under consideration, what are the 

 natural groupings of plants, and then what areas are occupied by the 

 several groups, after which a comparison with the soils, geological 

 formations, surface configuration, drainage and climatic influences 

 cannot fail to be productive of valuable results. 



The following natural groups are usually well marked, though of 

 course they merge into each other where there is a gradual transition 

 from the conditions favorable for one group, to those advantageous to 

 another. In some instances it is unquestionably true that other cir- 



