CHAPTER VI 



NATIVE VEGETATION AS AN INDICATOR OF 



ALKALI 



It is highly desirable that the prospective landowner 

 should, by studying the trees, shrubs, and grasses, be able 

 to say that the soil is deep, well-drained, fertile, free from 

 injurious properties, and capable of producing profitable 

 crops. Upon many soils the native plants tend to group 

 themselves to the exclusion of nearly all other species. 

 Generally when such grouping occurs, there is some pecu- 

 liarity of the soil which is made evident by such grouping. 

 The luxuriant growth of one species of plant to the exclu- 

 sion, or the near exclusion, of other species affords an 

 excellent index to the nature of the soil. 



How Plants Indicate the Soil. - - Certain plants in arid 

 regions are seldom found except when the soil contains 

 alkali salts. Davy investigating in California (i) states 

 that " there are at least 197 species natives of California, 

 which are restricted to alkali soils." Some of these plants 

 seem to thrive only when some particular salt is present 

 in certain strengths, resenting even small quantities of 

 other salts. Other plants do well in the presence of any of 

 the alkali salts so long as moisture or soil conditions are 

 right. In each portion of the arid region may be found 

 some plants which indicate extremely large quantities of 

 salts when found alone. They indicate that so much alkali 

 is present in the soil that the land is worthless for agri- 



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