[From the Bulletin of the Torrby Botanical Club 48: 315-326. 4 March, 1922. 



Phytogeographical notes on the Rocky Mountain region 



X. Grasslands and other open formations of the 



Montane Zone of the Southern Rockies 



Per Axel Rydberg 



In a previous article* I have discussed the wooded formations 

 of the Montane Zone. In this article the remaining formations 

 are taken up. In these, the plants of the plains and foothills 

 make up a larger proportion of the vegetation than in the wooded 

 formations. The river valleys, meadows, and hog backs have a 

 flora much more like that of similar habitats in the foothill region 

 and even on the plains. The transcontinental elements and those 

 from the prairie region are much more numerous. 



The formations have been arranged so that the hydrophytic 

 are first taken up and then the mesophytic, the most xerophytic 

 being left until the last. The species followed by a dagger, "f", 

 are confined to the Southern Rockies. 



A. AQUATIC FORMATIONS 



Lakes are not very common in the Montane Zone of the 

 Southern Rockies. In the higher parts they are mostly glacial, 

 fed by the snow fields, and contain little vegetation. The brooks 

 are swift and rarely form lakes or ponds in the higher regions. 

 Most of the lakes are found in the lower river valleys and " Parks " 



* Bull. Torrey Club 47: 441-454. 1920. 

 [The Bulletin for November (48: 285-314) was issued January 19, 1922.] 



315 



