300 



THE FORMATION 



is unnecessary that they be repeated. Similarly, the questions which pertain 

 to structure and development and to the surrounding vegetation are con- 

 sidered in detail in the pages which precede. 



Fig. 80. Eritrichiare ( Eritrichium arelioides), a community of the 

 alpine meadow formation. 



CLASSIFICATION AND RELATIONSHIP 



350. Bases. Formations may be grouped with reference to habitat or 

 kind, development or position. Classification upon the basis of habitat 

 places together formations which are similar in physiognomy and structure. 

 Developmental classification is based upon the fact that the stages of a par- 

 ticular succession are organically connected or related, though they are nor- 

 mally different in both physiognomy and structure. Grouping with respect 

 to position is made solely upon occurrence in the same division of vegeta- 

 tion. The formations thus brought together usually possess neither similar- 

 ity of kind or structure, nor do they have any necessary developmental con- 

 nection. Habitat and developmental classification are of fundamental value ; 

 regional arrangement is more superficial in character. All serve, however, 

 to emphasize different relations, and, while the developmental system ex- 

 presses the most, they should all be used to exhibit the vegetation of a region, 

 province, or zone. 



