CONTENTS. Vll 



Plant Ecology and Floristics of Sai/ton Sink — C!ontinued. p 



Mesophytic formation 96 



Mesophytic islets in the Mecca Flats 95 



Saliceta of Imperial Valley 9^ 



Xerophytic formation 96 



Some general characteristics of the xerophjrtic formation 96 



Age of the xerophytic trees and shrubs 98 



Absence of seedlings 98 



Associations of the xerophytic formation 99 



The detrital association 99 



Imperial association 100 



Mound association 100 



Travertine rock 100 



Trees of Salton Sink 101 



Analysis of the Flora 103 



Catalogue of plants collected in Salton Sink 104 



Movements of Vegetation Due to Submersion and Desiccation of Land Areas in the Salton Sink. 



By D. T. MacDougal 115-172 



Desert basins and revegetation 115 



The Salton Sink 116 



Laguna Maquata 118 



Plan of field work in the Salton Sink 119 



Facts to be ascertained 120 



Reoccupation of the strands of 1907 121 



Reoccupation of the strands of 1908 131 



Reoccupation of the strands of 1909 134 



Reoccupation of the strands of 1910 136 



Reoccupation of the strands of 1911 137 



Reoccupation of the strands of 1912 137 



Recession of 1913 138 



Influence of the lake upon the vegetation of the dry slopes above its level 139 



Endurance and survival of seeds and plants in place 140 



Possible invaders of the strands 141 



List of species appearing on the strands of Salton Sea 141 



Biological and physical conditions of dissemination and reoccupation 142 



Flotation and germination 144 



Occurrence and behavior of various species on the beaches 163 



The movements of plants into sterilized areas 169 



Historical 160 



The physical conditions of the Salton Sink 160 



Nature of the evidence 161 



Germination, flotation, and survival 161 



Species appearing earliest on the beaches 166 



Successions and eliminations 166 



Ancient strands 168 



The reoccupation of sterilized islands 168 



General Discussion. By D. T. MacDougal 173-182 



