XIV 



ILLUSTRATIONS. 



PAGE. 



Plate 57. Hi 



A. Carex-Agrostis association, Mount 



Rainier, Washington 234 



B. Lupinus volcanicus and Valeriana 



sitchensis society, Mount Rainier 234 



Plate 58. 



A. Abandoned farm, Wood, South Da- 



kota •• 238 



B. Field of corn and sudan grass during 



the drought of 1917, Glendive, 

 Montana 238 



Plate 59 



A. True prairie indicating agricultural 



land, Lincoln, Nebraska 240 



B. Oak chaparral indicating grazing 



land, Sonora, Texas ;■•;■■ 240 



C. Aspen, spruce and pine indicating 



forest land, Minnehaha, Colorado 240 



Plate 60. 



A. Artemisia filifolia indicating sandy 



soil, Canadian River, Texas 242 



B. Grama and buffalo-grass on hard- 



land, Goodwell, Oklahoma 242 



C. Atriplex nuttallii indicating non- 



agricultural saline land, Thomp- 

 son, Utah 242 



Plate 61. 



A. Tall valley sagebrush indicating a 



deep soil for irrigation, Garland, 

 Colorado :';V 256 



B. A legume, Lupinus plattensis, indi- 



cating a rich moist soil, Monroe 

 Canyon, Pine Ridge, Nebraska. . 256 



C. Relict Stipa and Balsamorhiza in 



sagebrush, indicating a bunch- 

 grass climate for dry-farming, 



Hagerman, Idaho 256 



Plate 62. 



A. Mixed prairie (Stipa comata) indi- 



cating dry-farming, Scenic, South 

 Dakota 252 



B. Tall-grass (Andropogon scoparius) 



indicating humid farming, Madi- 

 son, Nebraska 255 



C. Bunch-grass prairie (Agropyrum- 



Festuca) indicating dry-farming 

 with winter rainfall.The Dalles, 



Oregon 258 



Plate 63. 



A. Ruderal crop of Russian thistle, Sal- 



sola, in a field of feterita, Tulia, 

 Texas 268 



B. Ruderal crop of horseweed, Erigeron 



canadensis, in a fallow field, Good- 

 well, Oklahoma 262 



Plate 64. 



A. Grass type, Andropogon-Bulbilis- 



Bouteloua, Smoky Hill River, 

 Hays, Kansas 272 



B. Weed type, Erigeron, Geranium, etc., 



in aspen forest, Pike's Peak, Col- 

 orado 272 



C. Browse type, Artemisia tridentata, 



Beulah, Oregon 272 



PAGE. 



Plate 65. 



A. Savannah of desert scrub, Flourensia- 



Larrea-Prosopis, and desert plains 

 grasses, Bouteloua gracilis, erio- 

 poda and racemosa, Van Horn, 

 Texas 276 



B. Burn park in subalpine forest, Un- 



compahgre Plateau, Colorado . . 276 



C. Burn park of Wyethia and Artemisia 



in chaparral, Logan, Utah 276 



Plate 66. 



A. Grass park of Elymus and Agropyrum 



arising from sagebrush, Boise, 

 Idaho 278 



B. Sagebrush dying out as a result of 



competition with Agropyrum, 



Craig, Colorado 278 



Plate 67. 



A. Serai stages in sandhills, the sub- 



climax grasses Andropogon and 

 Calamovilfa, Agate, Nebraska. . . 280 



B. Serai stages in bad lands, Atriplex 



corrugata, nuttallii, and conferti- 

 folia the chief dominants, Cisco, 



Utah 280 



Plate 68. 



A. Bromus tectorum marking a burn in 



sagebrush, Boise, Idaho 282 



B. Erodium cicutarium indicating 



trampling in desert plains grass- 

 land, Oracle, Arizona 282 



Plate 69. 



A. Tobosa "swag," Hilaria and Sclero- 



pogon subclimax to desert plains 

 grassland, Las Cruces, New Mex- 

 ico 284 



B. Playa in the Bulbilis subclimax stage, 



the old shore-fine marked by 

 Euphorbia, Texhoma, Oklahoma. 284 

 Plate 70. 



A. Mixed turf of tall-grass (Agropyrum) 



and short-grass (Bulbilis), Win- 

 ner, South Dakota 286 



B. Pure turf of short-grass (Bulbilis), 



Ardmore, South Dakota 286 



Plate 71. 



A. Bouteloua-Aristida association in 



1917, Santa Rita Reserve, Tuc- 

 son, Arizona 292 



B. The same area in 1918 after serious 



drought and overgrazing by cat- 

 tle and rodents 292 



Plate 72. 



A. Denuded area about a kangaroo-rat 



mound in grassland, Santa Rita 

 Reserve, Tucson, Arizona 294 



B. General denudation by kangaroo- 



rats in desert scrub, Ajo, Arizona. 294 

 Plate 73. 



A. Relict Bouteloua and Aristida indi- 



cating former grass cover in des- 

 ert scrub, Tucson, Arizona. .... 296 



B. Relict Stipa and Balsamorhiza indi- 



cating replacement of grassland 

 by sagebrush, Hagerman, Mon- 

 tana 296 



