MV 



ILLUSTRATIONS. 



PAOB. 



Plats 67. 



A. Cam>Acrotk aatoeUtioo, Mount 



Bainkr. WMbiactoo 234 



B. LapiBiM Tnlwaifaw and ValeriuiA 



ritnhnwh tooltty. Mount Rainier 234 

 Plats ft& 



A. AbandoBod farm. Wood, South Da- 



koU 238 



B. Flald ol eom and midan graai during 



the drou^t of 1917. Glendive. 



Montana 238 



Plats W 



A True prairie indicating agricultural 



land. Lincoln, Nebraska 240 



B. Oak chaparral indicating gracing 



land. Sonora. Texas 240 



C. Aajmn, spruce and pine indicating 



forest land. Minnehaha, Colorado 240 

 Plats 60. 



A. Artemisia filifolia indicating sandy 



soil. Canadian River, Texas 242 



B. Grama and buffalo-grass on hard- 



land. Goodwell, Oklahoma 242 



C. Atriplez nuttallii indicating non- 



agricultural saline land, Thomp- 



on. Utah 242 



Plats 61. 



A. Tall valley sagebrush indicating a 



deep soU for irrigation, Garland, 

 Colorado 256 



B. A legume, Lupinua plattenais, indi- 



cating a rich moist soil, Monroe 

 Canyon. Pine Ridge, Nebraska. . 256 



C. BaBet Stipa and Balsamorhisa in 



cebrush, indicating a bunch- 

 grass climate for dry-farming. 



Hagerman. Idaho 256 



Plats 62. 



A. Mixed prairie (Stipa oomata) indi- 



cating dry-farming. Scenic, South ^ 

 Dakoto 25^ 



B. Tall-grass (Andropogon scopariua) 



indicating humid farming, Madi- ^ 

 on. Nebraska 2Si 



C. Bunch-grass prairie (Agropyrum- 



Festuca) indicating dry-farming 

 with winter rainfall.The Dalles. 



Oregon 258 



Plats 03. 



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 



Plats 64. 



A. Grass type, Andropogon-Bulbilis- 



Boateloua. Smoky Hill River, 

 Hays. Kansas 272 



B. Weed type. Erigecon, Geranium, etc., 



in aspen forest. Pike's Peak. Col- 

 orado 272 



C. Browse tsrpe, Artemisia tridentata, 



Beolah. Oregon 272 



PAOS. 



Plats 65. 



A. Savannah of desert scrub, Flourensia- 



Larrea-Prosopis, and desert plains 

 grasses, Bouteloua gracilis, erio- 

 poda and racemosa. Van Horn, 

 Texas 276 



B. Bum park in subalpine forest, Un- 



compahgre Plateau, Colorado . . 276 



C. Bum 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 

 Calamovilf a. 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 bum in 



sagebmsh, Boise, Idaho 282 



B. B}rodium 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. Play a in the Bulbilis subclimax stage, 



the old shore-line marked by 

 Euphorbia, Texhoma, Oklahoma. 284 

 Plate 70. 



A. Mixed turf of tall-grass (Agropyrxim) 



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 

 Plats 73. 



A. Reiict 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 



