PALOUSE PRAIRIE 



291 



precipitation falls in general during the four months from November 

 through February, while July and August may be practically rainless. 

 Because of the snow cover, the utilization of water is higher than in 

 the other associations and the grass cover is often unusually luxuriant 

 in consequence. 



Fig. 70. — ralou.^u piaiiic lu rtuulheu.-kni \\'a.-lnny,tuu ; Aij: ui.njium spicatum, 

 Festuca idahoensis, and Poa secunda chief dominants, with Koeleria and Stipa 

 less abundant. (Photo by A. L. Hafenrichter; courtesy of U. S. Soil Conser- 

 vation Service.) 



Dominants. The eudominants of the Palouse prairie are listed in 

 the first column: 



Agropyrum spication 



s-inerme 



smithi dasyslacfnjum 

 Stipa occidentalis 



o-elmeri 



o-thurberiana 

 Poa nevadensis 



Poa scabrella secundn 

 Agropyrum pauciflorum 



smilhi 

 Festuca idahoensis 



occidentalis 

 Stipa vindula 



comata 

 Elymus condensatus 



sitanion 



Elymus triticoides 



glaucus 

 Koeleria cristata 

 Melica harfordi 

 Danthonia californica 

 Oryzopsis hymenoides 

 Hordeum nodosum 

 Carex filijolia 



