CONTENTS. 



List of Illustrations. 



PAGE 

 V 



Introduction . 



PAGE 



1 



I. The Prairies. 



Panicum virgatum 4 



Andropogon furcatus 4 



Andropogon scoparius 



Andropogon nutans 5 



Stipa spartea 6 



Koeleria cristata 6 



Elymus canadensis 6 



Agropyrum repens 6 



Distichlis spicata 6 



Sporobolus longifolius 7 



Aristida oligantha 8 



Bulbilis dactyloides 8 



Bouteloua gracilis 8 



Liatris punctata 9 



Liatris scariosa 9 



Solidago rigida 9 



Solidago canadensis 11 



Silphium laciniatum 11 



Amorpha canescens 11 



Helianthus rigidus 11 



Brauneria pallida 11 



Petalostemon candidus 11 



Vernonia baldwinii 12 



Kuhnia glutinosa 12 



Verbena stricta 12 



Grindelia squarrosa 12 



Glycj'rrhiza lepidota 13 



Astragalus crassicarpus 13 



Psoralea tenuiflora 14 



Psoralea argophylla 14 



Baptisia bracteata 14 



The Suhclimax Prairie 15 



Brauneria pallida 15 



Lygodesmia guncea 16 



Lespedeza capitata 16 



Ceanothus ovatus 17 



Amorpha canescens 17 



Prairie Root Systems and Prairie Environ- 

 ment 18 



II. The Chaparral Community. 



Symphoricarpos vulgaris 25 



Rhus glabra 26 



Corylus americana 27 



Vitis vulpina 27 



Rosa arkansana 27 



Shrub Root Systems and the Shrub En- 

 vironment 28 



III. The Prairies of the Pacific Northwest. 



The Root Systems of the Grasses 31 



Agropyrum spicatum 31 



Festuca ovina ingrata 33 



Poa sandbergii 33 



Koeleria cristata 33 



The Root Systems of other Prairie Species . 33 



Lupinus ornatus 33 



Lupinus leucophyllus 35 



Astragalus arrectus 35 



Balsamorhiza sagittata 35 



Geranium viscosissimum 35 



Wyethia amplexicaulis 35 



Heuchera glabella 37 



Leptotsenia multifida 37 



Helianthella douglasii 37 



Hoorebekia racemosa 37 



Lithospermum ruderale 37 



Sieversia ciliata 37 



Sidalcea oregana 37 



Hieracium scouleri 38 



Potentilla blaschkeana 38 



Eriogoniun heracleoides 38 



Prairie Root Systems and Prairie Environ- 

 ment 38 



IV. The Plains Association. 



Bouteloua gracilis 46 



Aristida purpurea 46 



Muhlenbergia gracillima 47 



Gutierrezia sarothrae 49 



Psoralea tenuiflora 49 



Artemisia frigida 50 



Argemone platyceras 50 



Yucca glauca 61 



Agropyrum glaucum 52 



Carex pennsylvanica 52 



Andropogon scoparius 52 



Stipa comata 53 



Lithospermum linearifolium 53 



Lygodesmia juncea 53 



Aragallus lambertii 55 



Petalostemon purpureus 55 



Petalostemon candidus 57 



Eriogonum jamesii 57 



Ratibida columnaris 59 



Senecio aureus oblanceolatus 59 



Asclepias verticillata pumila 59 



Opuntia camanchica 61 



Opuntia f ragilis 62 



Plains Root Systems and the Plains En- 

 vironment 63 



