1881,] Botanizing on the Colorado Desert. 25 
good time, for as the objects of interest on this particular day’s 
march did not promise to be numerous, I intended to shorten as 
much as possible the hours of inevitable suffering from thirst. 
During the first half of the day a mirage, like a narrow sheet of 
placid water, just far enough away to dazzle and pain one’s eyes, 
kept always its allotted distance ahead. By the wayside and over 
all the plain, were scattered the shells of a certain fresh water 
mollusk of the genus Unio. The nearest stream is the Rio Col- 
orado, full a hundred miles distant, and these shells, now more 
than half dissolved and crumbling into scaly purple fragments 
when you touch them, must have been deposited here at a time 
when the Colorado had flooded the whole desert. No flower or > 
bird or insect were seen to-day to vary the monotony or break 
the silence. At noon I detected the shape of an adobe hut upon 
the tremulous horizon away to the left of the stage road, probably 
a mere ruin, but nevertheless suggestive of water, since no one 
ever built an adobe wall in this wilderness without first having 
found water. The first impulse was to turn aside and visit the 
spot. But as, through the varying medium of the heated air, the 
adobe at one moment seemed near, and the next very far off, so 
that I could not guess whether it was one mile away or five, I at 
second thought resolved not to waste time in what might prove 
a long and worse than fruitless deviation from my proper course. 
Before the afternoon was half gone my twenty-two miles journey 
was ended. I had reached the station of Indian Wells. The 
third day’s travel witnessed another change in the character of 
the soil. The ground becomes sandy, and instead of the grease 
wood of the alkali flats we have the much more sightly creasote 
bush (Larrea mexicana Morie), a bright evergreen with small 
foliage somewhat resembling that of the dwarf box, though the 
shrub has nothing of the close, compact habit of the box, and its 
slender spreading or rather drooping boughs bear yellow blos- 
soms among the leaves. 
The twigs when bruised exhale a strong odor of creasote, and 
they have stimulating properties. The Indians and Mexicans 
journeying across these parched wastes, chew them, and even tie 
bunches of them to the bits in the mouths of their ponies with 
good results in cases of extreme suffering from fatigue or thirst. 
This shrub occupies the sandiest parts of the desert, and usually 
where it occurs no other species of vegetation is found. 
VOL. XV.—NO. 1. 3 
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