1901] VEGETATION OF WESTERN TEXAS 287 
Salt lake basin (the Howard basin), it appears that the two types 
of vegetation on these alkaline flats are grass and chaparral 
formations. He says (doc. cit., p. 465) “the prevalent grass of 
the Pecos flats and often the only kind is Sporobolus airoides, with 
erect culm one to three feet high, and loose open panicle. It 
is distinctly salt to the taste,” etc. ‘On alkaline soils occur 
the fleshy chenopods Suaeda suffruticosa and S. depressa, and 
Spirostachys occidentalis.” Of the Howard basin he says (p. 497) 
“the smooth, broad beach of the lakes (occupying the center 
of this basin) more or less incrusted with alkali is absolutely 
bare. Here and there low sand hillocks are’ covered with 
Spirostachys occidentalis, Larrea Mexicana, and Frankenia Jamesii.” 
The salt grasses of the northern extremity of the basin consist 
mostly of Sporobolus airoides and S. Wrightii. 
Detailed information of the vegetation of alkaline basins 
or of the Gulf coast within the region here considered is not 
sufficient to warrant further discussion. 
CHANGES IN PREVALENT FORMATIONS DUE TO AGENCIES OF 
CIVILIZATION OR OTHER CAUSES. 
The equilibrium established upon the vegetation of the west 
Texas region as a resultant of all the forces playing upon it has 
been destroyed by the introduction of new forces chiefly due to 
human agency. Asa consequence, the vegetation of the region 
is undergoing some profound changes. Under the reign of 
equilibrium the trend was decidedly toward the establishment of 
solid grass formations, thus making the region one of open grass 
prairies and plains, The present trend is decidedly toward the 
establishment of woody vegetation, either shrubby or dwarfed 
arborescent, with a coincident driving out of sun-loving species 
(especially grasses) and favoring of the shade-loving ones. 
Other changes not in the direction of establishing a woody 
vegetation are taking place. For example, in the constitution 
of the grass formations Jared G. Smith observes (Bull. 16, U. S. 
Div. Agrost., p. 28) “before the ranges were overgrazed, the 
§tasses of the red prairies were largely blue stems or sage 
