The Alamogordo Desert 171 



pis shows many a handsome forest tree, and even the 

 mesquite in the Arizona Valley, where conditions are less 

 hard, rises a forest with trees fifty feet in height. The 

 cactus, as I read it, with undifferentiated floral leaves 

 and abundant sporophylls, is an ancient adaptation to 

 an ancient desert, possibly pre-cretaceous, and takes pos- 

 session of the world just so fast as the world becomes 

 desert; unstable in cultivation, not because new, but be- 

 cause reversionary. 



I do not mean to say necessarily that the Alamogordo 

 desert flora has had its origin where it stands, although 

 such a contingency is not impossible of thought. Had 

 this been the only desert on the continent its flora is as 

 might have been expected. But there are a hundred 

 similar intra-montane regions whose geologic history is 

 the same. These have in similar fashion orginally 

 shaped a flora each for itself. No doubt once similar 

 conditions are set up in regions at first unlike, an ex- 

 change of species may take place. American cacti are at 

 home in the deserts of Europe, and the Russian thistle 

 flourishes on Dakota plains. 



The desert lies shining here before us, changing for- 

 ever, but all its changes are of imperceptible delicacy 

 and slowness. Its methods would seem not different 

 from those by which nature has from the first essayed 

 the education of the vegetable world. Between salt water 

 and fresh all conditions offer by infinitesimal shadings 

 where the rivers meet the sea, thus green plants first 

 emerged from ocean; all conditions from shore-line low- 

 water mark to dry land; thus the plants at length sat 

 on the shore, wet only by tides or by the gentle rain; all 



