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RELATION TO ENVIRONMENT. 



1003. Summary of formations. 



I. Climatic (controlled by climatic factors). 



1. The woods or forest formation. 



2. The prairie formation. 



3. The plains formation. 



4. The desert formation. 



5. The arctic-alpine formations. 



II. Edaphic (controlled by ground factors). 



6. Edaphic or soil plant formations. 

 a. Rocky places. 



GENERAL b. Sand areas. 



FORMATIONS. | c. Marshes, moors, meadows. 



d. Alkaline areas, etc. 



III. Aquatic (controlled by bodies of water). 



7. The aquatic formations. 



a. Fresh-water formations. 



b. Salt-water formations. 



IV. Culture (controlled by man). 



8. The culture formations. 



a. Cultivated areas. 



b. Waste places. 



PRINCIPAL FORMATION (society) (controlled chiefly by distinct 

 physiographic areas). 



1. Layered. 



2. Zoned. 



3. Built up of vegetation forms. 

 Individual Formations (controlled by physical and biological 



factors). 



1. Layered. 



2. Zoned. 



(One or several facies make up the 

 formation) . 



1004. The terminology of plant communities is at present in 

 a very unsettled state, and it is necessary for nearly every writer 

 to define the terms and the limits of their application. Without 



