Southeastern Washington and Adjacent Idaho. 59 



valleys southward and westward. Here its size and abundance 

 make it an important floral component. Lupinus leucophyllus 

 is the most mesophytic of the group and is found at home typ- 

 ically on moist north slopes or in the valleys. 



In the lower ground considerable areas are given tone by the 

 white flowers of Galium. But with the increasing stress of 

 drought the aestival aspect passes, lingering only in moister situa- 

 tions. Then the leaden landscape of dry balsam-root, drying 

 grasses, and silvery-leaved lupines and hawkweed is relieved only 

 by the yellow and the blue of sparsely spaced goldenrods, asters, 

 and Hoorebekia. 



I have described very briefly the well developed prairie repre- 

 sented by the Festuca consociation. Westward and southward 

 as the altitude decreases and the rainfall is correspondingly less, 

 many important species either become fewer in individuals, or 

 are found only in the most mesophytic situations, or indeed dis- 

 appear entirely. Among these the following may be enumerated : 



Astragalus arrectus Leptotaenia multifida 



Carex geyeri Lithospermum ruderale 



Cirsium foliosum Potentilla blaschkeana 



Drymocallis convallaria Rosa nutkana 



Gaillardia aristata Rosa pisocarpa 



Galium boreale Sidalcea oregana 



Geranium viscosissimum Sieversia ciliata 



Helianthella douglasii Symphoricarpos racemosus 



Heuchera glabella Trillium petiolatum 



Hieracium scouleri Viola adunca 



Hoorebekia racemosa Wyethia amplexicaulis 



The Agropyron Consociation 



This community in an early stage of development covers hun- 

 dreds of acres of the thin soil in the scab-lands. The characteris- 

 tic plant is Agropyron spicatum. Areas characterized by this 

 consociation are peculiar because of the growth form of the domi- 

 nant species as well as a number of the commoner interstitials 

 which show various degrees of the same bunch habit. Numerous 



59 



