538 VEGETATION OF THE STEPPE. Book III. 
not be uninteresting in connection with the question relating 
to the gold-seeking ants of Herodotus. 
The Carrizo Creek is a brook rising in the moun- 
tains, running eastward through the denies of the desert, 
and finally losing itself there. Here we entered on quite 
a different country. Our way led us over the barren, tree- 
less, steep, and rocky heights of the southern part of the 
Californian mountains, where springs, surrounded by grass 
and a few poplars, exist only at great distances in some 
valleys. They have no permanent watercourses, but in 
the rainy season wild torrents sweep through them. 
During our first day's journey, from Carrizo Creek to 
Vallecito, we saw once more the vegetation of the Steppe 
in all its peculiarities. The sterile heights were almost ex- 
clusively overgrown with agaves and cactus, — a flora which 
I have nowhere seen so characteristic as in this locality. < 
It is the species of agave called Mezcal by the Mexicans, 
and the sweet root of which is collected by the Indians, 
baked and laid up for store. But the nearer we approached 
the coast of the Pacific, travelling west, the more humid 
grew the air, and accompanying this change in the climate 
a striking change appears in the flora which clothes the 
mountains. The heights are covered with evergreen 
shrubs, but here my botanic knowledge was altogether at 
fault. Here and there some evergreen oaks stood in the 
valleys, whilst the highest summits and ridges were for 
the first time covered with gigantic pine trees (Taxo- 
diums), for which California is remarkable. The growth of 
trees, however, is even here an exception, and this con- 
tinued the character of the country down to the shores of 
the Pacific. It may be asserted therefore, that with trifling 
interruptions the Steppe, beginning on the Missouri, extends 
on the one side through the territory of the Bio Grande as 
