( 1 ) Reed order, Phragmitetalia 



(a) Reed alliance, Phragmition, with the following asso- 

 ciations: 



Reed, Phragmitetum communis iowenses 



Bulrush, Scirpetum validi 



Cattail, Typhetum 



Reed canarygrass, Phalaridetum arundinaceae 



Sloughgrass, Spartinetum pectinatae 



(b) Sedge alliance, Magnocaricion, with one association: 



Sedge, Cancetum stnctae 



Conard points out that the classification he used permitted (1) 

 the arrangement of communities in a logical sequence from 

 aquatic habitats to grassland and woodland, (2) the showing of 

 similarities between communities on the basis of floristic com- 

 position, and (3) comparison with communities in other parts of 

 the world. 



The increasing emphasis on dominant and constant species by 

 those using the Braun-Blanquet procedures indicates an impor- 

 tant convergence of central and northern European methods, as 

 apparently there are no important or basic differences between 

 them.' ^ These procedures have been thoroughly tested recently in 

 Britain and their advantages pointed out,'^^ and they deserve far 

 more attention in America than they have received so far. '°^i°'''*^ 



The number of communities within a region distinguished by 

 these sociological attributes may be very large. For example, the 

 nitrophilous weed communities in the Eurosiberian Region of 

 Europe were classified and characterized into 132 associations, 

 26 alliances, 10 orders, and 6 classes, '^^ a work entailing very 

 many analyses of stands, numerous sociological tables, and de- 

 scriptions by many workers. These associations are eminently 

 suitable for differentiating the smallest communities in various 

 habitats, and in systematic classification they are indispensable. '^^ 



However, the small units are less suitable for describing the 

 vegetation of an extensive territory because of the difficulty of 

 gaining an over-all viewpoint. In order to solve this problem, 

 large units, called principal-associations (Hauptassoziationen), 



180 • Classificatiozm of Conmmmmxmities 



