11 



literature on the subject deals inadequately with the problems of 

 plant growth, root systems, transpiration losses, soil types, al- 

 kali conditions, and their relation to underground waters. Such 

 literature as exists is fragmentary and treats of these subjects, 

 if at all, more or less individually. Me Inzer (19) and other in- 

 vestigators, however, have assembled from various sources much 

 information in relation to ground-water plants and the depths at 

 which they seek moisture. Many desert plants have been listed by 

 them as indicators of ground water. 



The opportunity for such growth to send its roots to water 

 is naturally limited, as ground water in the desert is usually 

 beyond the reach of the root systems of plants. Nevertheless, 

 certain areas exist where it may be found. These are mostly in 

 the vicinity of surface lakes or desert playas {dry lakes) where 

 water is reasonably close to the surface. Because of soil evapo- 

 ration, areas overlying high ground water are likely to be strong- 

 ly alkaline and the vegetation which they support is of the salt- 

 resistant type. 



Ground-water areas are generally in the lowest portion of 

 a region. As the terrain rises towards the surrounding hills and 

 distance to water table increases, vegetation changes from the 

 salt-resistant succulents to the more bushy and woody types which 

 have roots developed for obtaining water from greater depths. 

 This arrangement inevitably results in irregular zones of vegeta- 

 tion arranged in the order of the ability of the roots to reach 

 the ground-water levels. Exceptions occur, however, where perco- 

 lating water from springs or occasional flows in normally dry 

 channels furnish a somewhat inadequate water supply for a precar- 

 ious growth. 



In the absence of comprehensive field studies relating to 

 the subject, a complete catalog of ground-water plants and the 

 depths to which their roots may go to secure water becomes im- 

 possible. Nevertheless, the relation of certain plant species 

 to water levels in the soil have been more or less adequately 



