Southeastern Washington and Adjacent Idaho. 61 



unoccupied soil surface, from 30 to 40 per cent., and the appear- 

 ance of several new species of a decidedly xerophytic stamp gives 

 this consocies quite a different physiognomy from the well de- 

 veloped prairies eastward. The following lists indicate the 

 dominant, principal, and secondary species : 



Composition of the Agropyron Consociation 



Dominant Species 

 Agropyron spicatum 



Principal Species 



Achillea millefolium var. lanu- Festuca ovina ingrata 



losa Lupinus ornatus 



Chrysothamnus nauseosus Lupinus sericeus 



Chrysothamnus nauseosus gra- Poa ampla 



veolens Poa sandbergii 



Chrysothamnus viscidiflorus Tetradymia canes c ens 



Festuca pacifica 



Secondary Species 



Agoseris heterophylla Epilobium paniculatum 



Allium acuminatum Erigeron corymbosus 



Alsine nit ens Erigeron hispidissimus 



Antennaria dimorpha Eriophyllum lanatum 



Artemisia rigida 5 Gilia pharnaceoides 



Astragalus collinus Koeleria cristata 



Astragalus spaldingii Lupinus wyethii 



Balsamorhiza sagittata Madia exigua 



Carex filifolia Madia glomerata 



Cirsium undulatum Phlox longifolia 



Clarkia pulchella Plantago purshii 



Cogswellia, triternata Potentilla biennis 



Elymus condensatus Stipa comata 



The rabbit brush, although more common westward, is an abun- 

 dant and conspicuous component of the bunch-grass community, 

 a Relict 



61 



