ROOT DEVELOPMENT IN THE GRASSLAND FORMATION. 



Plate 18. 



A. Andropogon furcatus, 4 months old. 



B. One-year-old Melilotus alba. 



Plate 19. 



A. Artemisia filifolia in sandy soil. 



B. Portion of root system of Psoralea 



tenuifiora. 



Plate 20. 



A. Rye grown in sandy soil to prevent wind 



erosion, Central City, Nebraska. 



B. Rye on sod, Colorado Springs, Colorado. 



Plate 21. 



A. Field of wheat at Colby, Kansas, where 

 roots were excavated. 



B. Field of wheat at Lincoln, Nebraska, 

 where roots were excavated. 

 Plate 22. 



A. Field of winter wheat (left) and spring 



wheat (right) on the hard land near 

 Limon, Colorado. 



B. Winter wheat on Pierre clay, Ardmore, 



South Dakota. 



C. Consocies of Stipa viridula in an aban- 



doned road. 

 Plate 23. 



A. Crop plats on lowland area, Lincoln, 



Nebraska. 



B. Crop plats on upland area, Lincoln, 



Nebraska. 



TEXT-FIGURES. 



1. Root system of Aster multiflorus. . . 



2. Root system of Solidago missourien- 



sis 



3. Roots and rhizome of Agropyrum 



glaucum 



4. Roots and rhizome of Spartina 



cynosuroides 



5. Salvia pitcheri 



6. Roots and rhizome of Helianthus 



rigidus 



7. Graphs showing the average daily 



evaporation rates in the mixed 

 prairie (upper line) and true 

 prairie (lower line) during 1919 



8. Graphs showing the average daily 



evaporation rates in the mixed 

 prairie (1918) and true prairie 

 (1916 and 1917) 



9. Graphs showing the average weekly 



day and night temperatures in 

 the mixed prairie (broken 

 lines) and true prairie (solid 

 lines) during 1919 



10. A meter quadrat in the mixed 



prairie community at Colorado 

 Springs, Colorado. A, An- 

 dropogon scoparius; Af, Ar- 

 temisia frigida; At, Aristida 

 pwrpurea/^^sN, Bouteloua gra- 

 cilis; Be, Bouteloua curtipen- 

 dula; Bo, Bozbera papposa; C, 

 Carex pennsylvanica; Ch, Chry- 

 sopsis villosa; K, Koderia cris- 

 tata; L, Lithospermum lineari- 

 folium; //// > Muhlenbergia 

 gracillima; P, Psoralea tenui- 

 fiora; Ps, Penlstemon angusti- 

 folius; R, Ratibida columnaris . 



11. A meter quadrat in the true prairie 



community at the upland sta- 

 tion at Lincoln, Nebraska. 

 A, Andropogon scoparius; Af, 

 Andropogon furcatus; Al, Al- 

 lium mutabile; Am, Amorpha 

 canescens; An, Andropogon nu- 

 tans; At, Aster multiflorus; B, 

 Bouteloua gracilis; Be, Boute- 



PAGE 



17 

 17 

 19 



19 



22 



24 



:;i 



32 



33 



34 



1.'. 



13. 



14, 



23 



loua curtipendula; C, Carex 

 pennsylvanica; E, Euphorbia 

 serpens; F, Festuca octoflora; 

 K, Kozleria cristata; L, Linum 

 sulcatum; Le, Lepidium vir- 

 ginicum; Li, Liatris punctata; 

 O, Oxalis stricta; P, Poa pra- 

 tensis; Pa, Panicum scribner- 

 ianum; S, Stipa spartea; So, 

 Solidago missouriensis; V, Viola 

 pedatifida 



Graphs showing the average daily 

 evaporation rates in the high 

 prairie (upper line) and low 

 prairie (lower line) at Lincoln, 

 Nebraska, during 1919 



A meter quadrat in the true-prairie 

 community at the lowland sta- 

 tion at Lincoln, Nebraska. 

 Af or /%y ', Andropogon furca- 

 tus; C, Choztochloa viridis; Ca, 

 Carex sp. ; E, Euphorbia macu- 

 lata; G, Glycyrrhiza lepidota; 

 O, Oxalis stricta; P or N \^X, 

 Poa pratensis; Pa, Panicum 

 virgatum; Ph, Physalis hetero- 

 phylla; Po, Polygonum muhlen- 

 bergii; S, Spartina cynosuroides; 

 So, Solidago altissima; T, Tri- 

 folium pratense 



Map showing stations in the grass- 

 land associations where studies 

 of root systems have been 

 made 



Root system of Paspalum setaceum . 



Erigeron bellidiastrum 



Corm and root system of Liatris 

 squarrosa 



Root system of Asclepias arenaria. . 



Haplopappus spinulosus 



Meriolix serrulata 



Mentzelia nuda 



Widely spreading and deeply pene- 

 trating root system of Eriogo- 

 num annuum 



Well-developed root system of Ar- 

 temisia canadensis 



37 



39 



42 

 45 

 46 



47 

 48 

 50 

 51 

 52 



53 

 59 



