THE PLANT FORMATION 



227 



disappeared from view, and Amovpha, Erigeron, Kuhnistera, and 

 Psoralea societies have taken tlieir place. The latter in turn 

 become inconspicuous as they stop flowering, and the character 

 of the autumn aspect is given by societies of Aster, Laciniaria^ 

 Helianthus, Solidago, etc. A society, moreover, is often char- 

 acterized by two or more principal species. Societies have no 

 essential connection with consocies. In any aspect, a consocies 

 may include several or many societies, or it may not show a single 

 one. Finally, a society may lie in two consocies, or it may occur 

 in any of them. 



241. The community. An inspection of plant societies shows 

 that thev are far from uniform. This is of course true of any 



Fig. 87. An Antennaria community of the aspen formation. 



intervals that occur between them. In both places cither i^rincipal 

 or secondary species may form minor groups called coninuinitios. 

 In many cases these are fairly definite and may be readily recognized. 

 In some instances, however, the number of species is so large and 

 the arrangement of the individuals so varying that distinct gi'oups 

 are lacking. Communities are easily recognizc<l in the case of 

 species where individuals grow in groups, and especially where 



