2. The Plains Formatiom. 
The Great Plains of the United States. 
tooth meridian to foothills and southwest to desert. 
Prevailing grasses. Bunch grasses (buffalo, beard and In- 
dian grasses). Here open formations. 
Other characteristic plants. 
Sage brush (Artemgsia tridentata). 
Prickly pear cactus (Opuntia). 
Semidesert flora of southwest and Mexico tablelands. 
Cacti, yucca, succulents. : 
Coarse shrubby growths (ex. Mesquit tree). 
Sage brush and bunch grasses. 
4. Edaphic Formations in Prairie Regions. 
Different Areas. 
I. Rivers (Forest and true meadows). 
2, Sand tuls: 
3. Alkali areas and Bad lands. 
Forest formations. 
Eastern element meets western element along Niobrara river 
(Pinus 'scopularum from Rockies). 
Meadows, along river courses and around lakes. 
Intermediate between forest and prairie. 
Elymus canadensis. 
Long stemmed “sod formers” Stipa spartea. 
Agropyron pseuddrepens, etc. 
Subordinate, “Bunch grasses.” 
Sand-hilis in Nebraska, 
Beard grass (A. scoparius) is dominant species. 
Open formation. 
Subordinate plants in Sand-hills. 
Xerophytic shrubs, herbs and other grasses. 
Spring or vernal flora. 
Cat’s foot (Antennaria campestris). 
Fennel leaved parsley (Peucedanum foeniculaceum). 
Prairie clovers, etc. | 
Summer autumnal flora. 
Golden rods, verbenas, amorpha, etc. 
Sand plains, another beard grass (A. furcatus is dominant 
and formation closer, though often open). 
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