THE AMERICAN DESERTS 



THE series of pictures on pages 

 1 52-1 6 1 illustrate the marvel- 

 ous strength of desert plants. 

 The size and luxuriance of the plants 

 prove their wonderful vigor; but we are 

 at a loss to explain the source or reason 

 of their prosperity in regions where only 

 a few inches of water fall during the 

 year, and that little is immediately 

 drunk up by the torrid sun. What en- 

 ables the yucca (page 158) to thrust its 

 head through thirty feet of gypsum 

 sand, or the barrel cactus (page 158) to 

 store enormous quantities of water, and 

 to hold the water for months, perhaps 

 years, or the sumach (page 156) to 

 cling so tenaciously to its ground when 

 everything else is swept away, are ques- 

 tions which none can satisfactorily an- 

 swer. No less marvelous and inexpli- 

 cable are the mesquite shrub, which 

 sometimes has roots over fifty feet long, 

 and other desert plants whose hairy 

 coverings and resinous coatings prevent 

 the evaporation of moisture. 



On his return from the Death Valleyex- 

 peditionin 1891, Mr Frederick V.Coville 

 was so impressed with the necessity of 

 thoroughly understanding the strength 

 of desert plants that he planned the es- 

 tablishment of a desert botanical labora- 

 tory. His botanical explorations in the 

 Death Valley had enabled him to recog- 

 nize the major problems of such an in- 

 vestigation, and to outline plans for fur- 

 ther researches. The importance of 

 such work was seen at once, but it re- 

 quired much more time and money than 

 were available. When the Carnegie 

 Institution was established Mr Coville 

 presented his long-cherished project. 

 The board approved the plan and made 

 a grant to build a laboratory at Tucson 

 and to carry on researches at this point. 

 The experiments, directed by Mr Co- 

 ville and Dr D. T. MacDougal, are 

 under the immediate care of Dr W. A. 

 Cannon, as resident investigator, and 



their object at present is to investigate 

 the special devices of desert plants for 

 the absorption and storage of water and 

 for resisting substrata of unusual com- 

 position, like the gypsum sands of the 

 Tularosa Desert. 



A complete solution of the mysterious 

 strength of desert plants will prove of 

 great economic value to the United 

 States aside from the important informa- 

 tion it will give regarding the funda- 

 mental processes of protoplasm. In for- 

 mer times bands of roaming Indians 

 inhabited the desert regions of the south- 

 west. They lived in comparative abun- 

 dance, and yet the country was no less 

 arid than it is today. Doubtless they 

 obtained food from the plants of the 

 desert just as easily as the Papago In- 

 dian shown on page 158 is obtaining 

 drinking water from the barrel cactus. 

 White men can do likewise as soon as 

 they understand these plants, and will 

 find many practical uses for the cactus 

 and yucca. An understanding of the 

 source of strength of desert plants will 

 also enable the farmer who irrigates his 

 semi-arid land to judge how much water 

 to apply and how often in order to gain 

 the best results. It will also help him 

 to develop alkali and drouth-resistant 

 types and thus to reclaim new areas. 



The first report of the laboratory has 

 been published by the Carnegie Institu- 

 tion.* It describes a systematic tour of 

 the deserts by Messrs Coville and Mac- 

 Dougal in 1903 and gives a useful ac- 

 count of the characteristic vegetation of 

 the different deserts. It is superbly illus- 

 trated with 29 plates, from which those 

 given in this abstract are selected. 

 Tucson was chosen as the site of the lab- 

 oratory because it has a climate of a 

 thoroughly desert character and a rich 



* Desert Botanical Laboratory of the Carne- 

 gie Institution. By Frederick V. Coville and 

 D. T. MacDougal, Washington, Carnegie In- 

 stitution, 1903. 



