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BOTANY OF THE DEATH VALLEY EXPEDITION. 



Ey Frederick Vernon Coville, 



PREFATORY NOTE. 



In 1880 and subsequent years appropriation was made by Congress 

 for a study of the geographic distribution of animals, to be conducted 

 by the Division of Ornithology and Mammalogy, United States De- 

 partment of Agriculture. In the year 1890 the scope of the work 

 was enlarged by act of Congress so as to include the distribution of 

 plants as well as animals, and in accordance with this provision the 

 writer was temporarily detailed from the Division of Botany as bot- 

 anist of the Death Valley Expedition, the first of the biological sur- 

 veys under the new act. The work was planned and conducted under 

 the direction of Dr. C. Hart Merriam, chief of the Division of Orni- 

 thology and Mammalogy. The botanical work undertaken by the 

 writer was to collect and identify the plants of the region traversed by 

 the expedition, to collate those data which had reference to the 

 range of species, and to arrange this accumulated material in such 

 form that it would be useful in studying the facts and problems of 

 geographic distribution. The subject-matter of the report is presented 

 under the following heads: 



(1) Itinerary — a record of the writer's location each day after leav- 

 ing San Bernardino, with a few references to those prominent features 

 of the route which are of especial L>otanical interest. 



(2) Principles of plant distribution — an enumeration of the main 

 conditions influencing distribution, and an attempt to reduce these con- 

 ditions to their simplest factors. 



(3) Distribution of plants in southeastern California — an analysis of 

 the flora of that region into its smaller component floras, and a con- 

 sideration of their relation to each other and to the floras of adjacent 

 parts of the country. 



(4) Characteristics and adaptations of the desert flora — a statement 

 of the environmental conditions of the Death Valley desert region, 

 and a discussion of the resultant adaptive modilicatious of the flora. 



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13095— No. 1 1 



