4 2 A Study of the Vegetation of 



The Festuca Consociation 



This consociation occupies the larger part of the area covered 

 by the prairie-plains formation. Along the thin soils of the 

 canyons the ecotone between this and the Agropyron consociation 

 is often very sharp, but westward and southward it shades im- 

 perceptibly into the latter. 



The plants that share in the botanical composition of this con- 

 sociation in eastern Washington and adjacent Idaho are given 

 in the following lists of species which are classified into three 

 groups based upon their relative abundance and ecological im- 

 portance. 



Composition of the Festuca Consociation 

 Dominant Species 



Agropyron spicatum (includ- Festuca ovina ingrata 



ing var. inerme) 2 Koeleria cristata 



Balsamorhiza sagittata Poa sandbergii 



Principal Species 



Achillea millefolium lanulosa Leptotaenia multifida 



Astragalus arrectus Lupinus ornatus 



Erythronium grandiflorum Potentilla blaschkeana 



Geranium viscosissirnum Rosa nutkana 



Helianthella douglasii Sieversia ciliata 



Hoorebekia racemosa Symphoricarpos racemosus 

 Hieracium scouleri 



Secondary Species 



Agoseris grandifiora Arnica fulgens 



Agoseris heterophylla Aster fremonti 



Allium acuminatum Aster laevis geveri 



Alsine nit ens Astragalus spaldingii 



Antennaria luzuloides Bromus brizaeformis 



Apocynum pumilum Bromus hordeaceus 



2 The nomenclature in this paper is that of the Flora of Southeastern 

 Washington and Adjacent Idaho, by C. V. Piper and R. Kent Beattie, 1914. 



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