Rydberg: Phytogeographical notes 633 



sides of the Northern Rockies. The grass flora of the mountain 

 sides is of the following composition : 



Stipa minor Festuca ingrata 



* " Nelsonii t " saximontana 



Agrostis hiemalis Bromus Richardsonii 



Trisetum subspicatum " Pumpellianus 



" majiis Agropyron andinum 



Poa longiligida " Scrihneri 



" paddensis " violaceum 



" epilis 



" confusa 



" laevigata 



The following are restricted to one region : 



Southern Rockies 



Muhlenbergia gracilis Poa Fendleriana 



" suhalpina " Sheldonii 



Poa aperta Bromus Porteri 

 " longipedunculata 



Northern Rockies 



*Poa Cusickii \ Agropyron latiglume 



" nevadensis 



Southern slope of the Southern Rockies 



On the more xerophytic southern slopes of the Rockies of 

 Colorado and New Mexico, the following species are the char- 

 acteristic ones: 



Trichachne saccharatum Festuca arizonica 



Poa crocata " Thurberi 



" Fendleriana t " -saximontana 



5. Hog-backs 



As stated before, the grass flora of the hog-backs or exposed 

 ridges is practically the same as that of the rock-crests of the 

 alpine region, except that a few of the more mesophytic grasses, 

 as for instance Trisetum subspicatum and DescJiampsia curtifolia,, 

 are lacking. A few species from the Montane Zone are added. 



