4 Muhlenbergia, Volume 6 



RECENT LITERATURE 



Distribution and Movements of Desert Plants. By Vol- 



ney M. Spalding. Carnegie Institution, Washington, D. C. 



1909. Pp. 144. Plates 1 -3 1. 



This able paper is concerned, primarily, with an investiga- 

 tion of the edaphic and ecological relations of the plant cover- 

 ing of the domain of the Desert Botanical Laboratory, an area 

 of some four square miles near Tucson, Arizona. The tract in- 

 cludes Tumamoc Hill, on whose northern slope the Laboratory 

 buildings are situated, and which rears its flattened summit 3092 

 feet above sea level, and 742 feet above the flood plain of the 

 Santa Cruz river, as well as a part of that plain, and of the inter- 

 vening mesa-like slopes. The hill is cut, and in a limited sense 

 drained, by a characteristic desert wash, with its tributary gul- 

 lies. The Santa Cruz is a typical "river" of the arid west; in 

 flood a raging and eroding torrent, soon becoming a feeble stream, 

 and for much of the time a bed of bare sand, whose only moist- 

 ure is beneath the surface. The domain also shares in the dual 

 annual vegetation which twice each year clothes the scorched 

 plains and hills of Arizona with a brief but luxuriant growth of 

 fundamentally different plants, responsive respectively to the 

 winter and to the summer rains. 



It will be seen therefore, that limited as is this area, it is 

 fairly representative of the topography of the whole region, with 

 the exception of the higher mountains. Within its bounds 

 grow the few hydrophytes of the river pools and the irrigation 

 ditches, the equally scanty mesophytes of the river banks, the 

 halophytes of the alkaline "salt spots," and above all the abund- 

 ant and varied xerophytic vegetation of the mesa and hill slopes. 



Long and careful study has been given to these various 

 plant associations; both over the general area, and of small tracts 

 especially marked out for comparative observation; and the 

 whole- has been supplemented by work in other desert localities. 

 To a description of these researches, and to an account of some 

 of_ the interesting and instructive deductions drawn from them 

 the paper is devoted. Five typical plants, as representatives of 



