PLANT ASSOCIATIONS 



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As stated in the preceding chapter, there are in each plant associa- 

 tion certain species of plants that are called dominant species be- 

 cause they in a large measure exert a controlling influence upon the 

 environment. There may be only a single dominant species or there 

 may be several and the other species that are growing along with the 

 dominant plants are called secondary species. The associations are 

 named from the dominant species. Thus we may speak of the sage 

 brush association, meaning an association in which sage brush is 

 dominant, or we may speak of an oak-hickory association (Fig. 83), 

 or of a beech-maple-hemlock association. The scientific names of 



Fig. 83. — An oak-hickory association. 



the dominant plants may be used instead of the common names, as, 

 for example, the Artemisia association, the Acer saccharum associa- 

 tion, or the Quercus-Carya association. 



The term, plant association, may be used in either the concrete or 

 the abstract sense. For example, we may speak of a particular plant 

 community as an oak-hickory association in which case we would be 

 using the term in the concrete sense, or we may say that the oak- 

 hickory association is characteristic of the drier uplands throughout 

 Indiana in which case we are using it in the abstract sense. This 

 practice is, of course, no different than the common usage of the 

 names of individual plants. In speaking of an individual tree, for 

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