1904} SPALDING—THE CREOSOTE BUSH 123 
remarkable adaptations to desert conditions, and present striking 
examples of survival in a region that has passed from widely different 
conditions at an earlier geological period to its present. extreme 
~~ ‘s : hs J a ae at 
as ee ag. 
. _ ey, 4 ¥ 
= a? \N : % 
Te 
FE Covillea tridentata, near 
IG. 
Gard. No. 46° Plant World 6: pl. 36. 
i. 4 
Tucson, Arizona.—From Contrib. N. Y. Bot. 
t the 
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aridity. Work on these several species is now under way 
Desert Laboratory of the Carnegie Institution, and as yet is incom- 
plete. It is thought best, however, to embody in the form of a report 
