THE ECOLOGICAL RELATIONS OF THE VEGETA- 
TION OF WESTERN TEXAS. 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY. 
WILLIAM L. BRAY. 
(WITH TWENTY-FOUR TEXT FIGURES ) 
WesTERN Texas has been a choice field for botanists from 
the earliest days, always having been accessible through the 
humerous army posts and government surveys. For this reason 
the flora early became fairly well known through numerous con- 
tributions describing the country and its vegetation, and from 
descriptions of species, culminating in the Botany of Western 
Texas by Professor Coulter, Since that time, the study of 
plants in their natural environments has enriched botanical 
thought, and it seems opportune to take up again the flora of 
western Texas and to apply to it the new methods. 
A further reason for presenting the plant life of Texas as the 
product of its environment lies in the growing tendency to rely 
upon such study to furnish a rational basis for the exploitation 
of plant life in agriculture, horticulture, forestry, agrostology, 
and various other economic fields. The great diversities of 
climatic factors, of soils, and of physiographic conditions in the 
Texas region make it necessary to find the results of these fac- 
tors as recorded in plants already occupying the field, that 
they may serve as a guide in attempting to introduce new ones. 
The statement that the flora of western Texas early came to be 
fairly well known is true only of pteridophytes and spermato- 
phytes, for the bryophytes and thallophytes have scarcely been 
noticed thus far. 
_ The present paper aims only to clear the field a little, prepar- 
atory to its cultivation along special lines; and because it is a 
very large field, with much to be done, it offers a strong 
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