26 ANIMAL LIFE OF CARLSBAD CAVERN 



In Garden Canyon just over the ridge from the big 

 cave, as in many canyons higher toward the mountains, 

 grow the New Mexico locust trees, similar to the fragrant 

 eastern locust, but with delicate pink instead of pure 

 white racemes of fragrant flowers; a wonderful flowering 

 tree that should be more widely under cultivation. 



SHRUBBY VEGETATION 



In the rigorous climate of arid regions with re- 

 duced rainfall and rapid evaporation, extremes of 

 summer heat and sudden changes to severe cold, where 

 the half-naked soils are deprived of the mellowing 

 effects of winter snows, and often are exposed to severe 

 winds that beat the branches and tug at the stems of 

 such hardy plants as are able to withstand the fierce 

 onslaught, it is not strange that the vegetation should 

 take on weird forms. To such plants as persist through 

 it all come long mild days of clear sunlight, and after 

 occasional showers, moist balmy nights, and days of 

 intense growing activity, the desert blooms in won- 

 derful beauty. Under no other conditions are the 

 survival of the fittest or the elimination of the unfit 

 more marked than in these arid regions of great ex- 

 tremes, where forests are replaced by low shrubs and 

 every plant is protected by some form of armor, or has 

 means of defense against destruction. Naturally, 

 under such adverse conditions, strange types of vegeta- 

 tion have developed. Some are highly modified forms 

 of common and widespread groups from the north or 

 south. Others are of restricted range and are not 

 found beyond the limits of the semideeert region. Each 



