[Reprinted from The Plant World, Vol. VI, No. 11, November, 1903.] 



Some Aspects of Desert Vegetation. 



By D. T, MacDougal. 



A SERIOUS investigation of some of the numerous problems presented 

 by the xerophytic vegetation of arid regions has recently been made 

 possible by the establishment of the Desert Botanical Laboratory of the 

 Carnegie Institution, which has been located at Tucson, Arizona. While 

 any of the more important phases of botany might be the subject of 

 investigation by means of the facilities offered by this laboratory, yet its 

 special function consists of an inquiry into the morphology, physiology, 

 habit and general life-history of the species indigenous to the deserts of 

 North America, an area which amounts to more than a million square 

 miles. 



The conditions afforded vegetation in these districts show such wide 

 departures from those of humid temperate, and those of tropical regions ; 

 the living flora is accessible to so few workers and the entailed investigations 

 are necessarily so wide in scope, so extensive and difficult in execution, 

 that the advance of knowledge of the life of desert plants has been com- 

 paratively slow. Nearly a decade has elapsed since any notable investi- 

 gations have been made upon xerophytic vegetation as such, and in that 

 period morphology and physiology have made a marked general advance, 

 while heredity and the origin of species have taken on a renewed interest 

 because of the results brought to light within the last few years. It may 

 be expected therefore that a searching study of the vegetation of arid 

 regions will afford information concerning the fundamental processes of 



