CONTENTS. 



List of illustrations. 



PAGE 



5 | Introduction. 



I. The Prairie-Plains Grassland Formation. 



The true prairie 



The short-grass plains. 



12 

 13 



The mixed prairie . 



page 

 9 



11 



II. Root Systems of Trtje-Prairie Species. 



Aster multiflorus 



Solidago missouriensis . 

 Agropyrum glaucum . . 



Poa pratensis 



Spartina cynosuroides. 



Salvia pitcheri 



Melilotus alba 



Helianthus rigidus 



16 

 16 

 18 

 18 

 21 

 21 

 23 

 23 



Prairie Root Systems and Prairie En- 

 vironment 



Summary of Prairie Species 



Comparison of True- and Mixed-Prairie 

 Environment 



Comparison of High and Low True- 

 Prairie Areas 



25 

 2.5 



27 

 37 



III. Root Systems of Short-Grass-Plains Species. 



Opuntia polyacantha. 



43 | Schedonnardus paniculatus 43 



IV. Root Systems of Mixed-Prairie Species. 



Species Excavated in Sandy Soil: 



Paspalum setaceum 



Erigeron bellidiastrum 



Liatris squarrosa 



Asclepias arenaria 



Haplopappus spinulosus 



Meriolix serrulata 



Mentzelia nuda 



Eriogonum annuum 



Onagra biennis 



Commelina virginica 



Pentstemon angustifolius .... 



Cyperus schweinitzii 



Thelesperma gracile 



Ceanothus ovatus 



Croton texensis 



45 

 46 

 47 

 48 

 49 

 49 

 50 

 51 

 54 

 55 

 55 

 56 

 56 

 57 

 58 



Species Excavated in Sandy Soil- 



Artemisia canadensis 



Anogra cinerea 



Chrysopsis hispida 



Pentstemon ambiguus 



Panicum scribnerianum .... 

 Tradescantia occidentalis. . . 

 Bouteloua hirsuta 



-con't. 



Species excavated in Hard Lands: 



Bouteloua curtipendula 



Stipa viridula 



Astragalus microlobus 



Eriocoma cuspidata 



Carex filifolia 



Astragalus drummondii 



59 

 61 

 61 

 62 

 65 

 65 

 65 



67 

 68 

 69 

 69 

 70 

 70 



V. Ecads. 



Bulbilis dactyloides 



Bouteloua gracilis 



Agropyrum glaucum 



Gutierrezia sarothrse 



Petalostemon purpureus. 



Lygodesmia juncea 



Andropogon scoparius . . . 



Andropogon furcatus 



Artemisia filifolia 



Muhlenbergia pungens . . 



Central City, Nebraska . 

 Lincoln, Nebraska 



Yuma, Colorado . . 

 Sterling, Colorado. 

 Flagler, Colorado . . 



72 

 77 

 77 

 78 

 78 

 79 

 79 

 82 

 82 

 82 



Aristida purpurea 



Psoralea tenuiflora 



Artemisia frigida 



Chrysopsis villosa 



Carex pennsylvanica 



Redfieldia flexuosa 



Calamovilfa longifolia .... 



Andropogon hallii 



Summary of Short-grass 



Mixed-Prairie Species . . 



Conclusions 



Plains and 



VI. The Root Systems of Cereals. 

 Root Development in True Prairie. 



100 

 101 



Fairbury, Nebraska. 

 Wahoo, Nebraska. . 



Root Development in Short-Grass Plains. 



108 

 109 

 109 



Burlington, Colorado. 



Colby, Kansas 



Limon, Colorado 



83 



85 

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 87 

 88 

 88 

 89 

 89 



92 

 92 



105 

 106 



112 

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114 



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