National Geographic : 1904 Apr
THE AMERICAN DESERTS THE series of pictures on pages 152-161 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 DeathValleyex pedition in 189 , 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.