﻿632 Rydberg: Phytogeographical notes 



The following mesophytic grasses, which could be counted 

 among the meadow-grasses, prefer, however, river banks more 

 or less covered by shrubbery. 



Trisetum montanum 

 *Elymus glaucus 



3. Dry Valleys and Bench-lands 

 Sometimes the sides of the valleys slope gently and the meadow 

 passes gradually into the dryer part of tlie valley and this into 

 the mountain side, sometimes the sides rise in a series of steps or 

 shelves, one above the other. These steps are the remains of 

 former river-banks or lake-shores. They are known as benches. 

 The grasses of the bench-lands and other drier portions of the 

 valleys are decidedly xerophytic. They consist mostly of genera 

 which are characteristic of the Great Plains or the Foot-hills. 

 In the Subalpine Zone the bench-lands are not often found 

 and are always of insignificant area. The following grasses are 

 characteristic of the bench-lands of the Subalpine Zone : 

 Stipa Tweedyi Bromus Porteri 



minor " Richardsonii 



Poa crocata " polyanthos 



longiligula Agropyron violaceum 



" lucida Elymus simplex 



" Buckley ana 



4. Mountain Slopes 

 Sometimes the meadow passes gradually into the mountain 

 slopes, w^ithout any intervening xerophytic region. The mountain 

 grass-slope is often mesophytic in its nature, especially in the 

 Subalpine Zone, and is much like that of the Alpine Zone. In the 

 Northern Rockies the most important grass of such mountain sides 

 is Festuca ingrata, which, however, has its best development in the 

 Montane Zone. This grass is also common in the northern part 

 of the Southern Rockies, but on the southern slopes of the latter 

 its place is taken by Festuca arizonica and F. Thurberi. The 

 latter for instance covers all the southern slopes of the Abajo 

 Mountains in southeastern Utah, almost to the top (3,300 m. alt.). 

 These slopes, however, are more xerophytic than the mountain 



