CLASSIFICATION OP SERES. 



183 



upon the basis of the agents concerned in producing bare areas. While this 

 has value in connection with the origin of such areas, it is not fundamental, and 

 hence is out of place in a developmental classification (plate 52, a, b). 



Phylogenetic system. — ^The arrangement proposed above deals with the 

 grouping of seres within a particular climax. It applies to the relations of 

 existing seres, as well as to those of each period 

 or era and sums up the ontogeny of the cUmax 

 formation. The phylogenetic relations of the 

 latter obviously must be sought in the geological 

 past. They serve to show the immediate origin 

 of the climaxes of to-day, and to summarize the 

 lines of vegetational descent in the remote past. 

 The outstanding relationships of the great vege- 

 tations of the eras are sketched in Chapters XII 

 to XIV. The application of the classification 

 here proposed to the present vegetation of 

 North America and Europe will be found in the 

 following two chapters. The complete system 

 of classification is shown in the accompanying 

 outline. 



Geosere. 

 Eosere. 

 Clisere. 

 Cosere. 

 Sere (climax). 

 Prisere. 

 Hydrosere. 

 Halosere. 

 Oxysere. 

 Xerosere. 

 Lithosere. 

 Fsammosere. 

 Subsere. 

 Hydrosere. 

 Xerosere. 



