36 DESERT BOTANICAL LABORATORY 



the Tularosa desert north of the Rio Grande have already been men- 

 tioned. The Jornada del Muerto (Journey of Death) of the ancient 

 Spanish explorers lies in the western portion of the Chihuahua desert 

 in New Mexico separated from the Tularosa desert by the Organ 

 mountains. Further northward the great stretches of malpais^ or black 

 volcanic rock, form a desert district of the extreme type, while numer- 

 ous areas are impregnated with alkali, and are either almost wholly free 

 from vegetation or support only halophytic species. The Bad Lands 

 of Dakota owe their desert character to the peculiar composition of the 

 soil which is clayey, poor in nutrient substances, and subject to great 

 erosion so that extensive areas are destitute of vegetation of any kind. 



Observations upon the striking forms of xerophytic vegetation char- 

 acteristic of arid regions have been made by occasional explorers in 

 various parts of the world ; among these are to be noted the writings 

 of Philippi on the desert of Atacama on the west coast of South 

 America, published in i860. The accounts of the earlier surveys of 

 western America also contain some interesting information concerning 

 some of the features of the flora of the desert regions. The first gen- 

 eral studies of the flora of arid regions were made by Volkens and 

 by Maury, whose results were published in 1887 and 1888. 



Volkens made some examination of the physiographic and climatic 

 conditions in the deserts of Arabia and Egypt and also of the relation 

 to habitat of some of the characteristic species. His treatment of the 

 functional performances of xerophytic plants indigenous to this region 

 is based upon anatomical characters almost wholly, and no effort 

 appears to have been made to measure the actual work acccomplished 

 by the plant under any of the conditions described. The detailed 

 study made of the general structure and vegetative habit of a large 

 number of species resulted in the acquisition of a rich mass of anatom- 

 ical facts, upon which our present knowledge of the properties of desert 

 plants chiefly rests. 



Maury also made an examination of the general features of the mi- 

 nute anatomy of xerophytic plants from the Sahara region, and sets 

 forth the principal adaptations which these species have undergone in 

 response to their arid environment. 



The work of Warming upon the flora of the dry savannas at Lagoa 

 Santa in Brazil is also to be regarded as an important contribution to 

 the general subject of desert vegetation. A fairly complete bibliogra- 

 phy of the entire subject forms the concluding section of this report. 



In 1 89 1 Mr. Frederick V. Coville made a botanical investigation of 

 the Death Vallev region in southern California. The work was de- 



