THE DESERTS AND DESERT 

 FLORA OF THE WEST 



BY LEROY ABRAMS 



Associate Professor of Botany, 

 Stanford University 



THE American deserts, like the mirages that 

 hover over their surfaces, are ever receding 

 as man advances. Our grandfathers were 

 taught in their youth that the territory between the 

 Rocky Mountains and the Missouri River was a 

 desert waste, — ^the Great American Desert, void of 

 vegetation and uninhabitable. To-day we speak of 

 the Colorado Desert, unmindful that what was at 

 one time its bleakest and most forbidding part, 

 where travelers by the score have perished from 

 heat and thirst, has been transformed into a pro- 

 ductive valley, the second largest in California, 

 with a dozen or more flourishing towns surrounded 

 by alfalfa, grain and cotton fields, orange groves, 

 vineyards and dairies. Skillful engineers are pene- 

 trating the deserts with railroads and irrigation 

 systems. Pioneers are converting their barren 

 wastes into fertile fields. But finally, when man's 

 resources are exhausted, large areas too rough and 

 inaccessible for profitable cultivation, will remain 

 undisturbed, harboring the native desert life. In 

 outlining the deserts of North America, therefore, 

 we may include all of the naturally arid region 

 within which may be found many valleys made 

 ri6h and productive by irrigation. 



Desert Regions of North America. — The arid 

 areas of western North America fall into two 

 natural divisions, the Great American and Mexican 

 plateau regions lying east of the Continental Divide, 

 and the Great Basin and Sonoran regions lying be- 

 tween the Continental Divide and the Pacific 

 mountain systems. Roughly speaking, the plateau 

 regions east of the Continental Divide include the 

 Bad Lands of Dakota and Montana, the Red Desert 

 of Wyoming, the Staked Plains of Texas, and the 

 Mexican tablelands east of the Sierra Madre from 

 San Luis Potosi to southwestern Texas and New 

 Mexico. The western division, or Great Basin and 

 Sonoran regions, is the territory with which we are 

 at present concerned. Of this, the Great Basin 

 region embraces the sage-brush plains of eastern 

 Washington, eastern Oregon and southern Idaho, 

 the closed basins of Utah and Nevada, and the 

 Mohave Desert of southern California, while the 

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