VEGETATION OF THE PRAIRIE. 



563 



are pyramidal or conical, flat-topped hills (buttes) with very 

 precipitous sides, and between them canyons. The sides of 

 the buttes, cliffs, and canyons erode rapidly during rains. The 

 characteristic plants are the greasewood, a spiny shrub (Sar- 

 cobatus vermiculatus) a meter (3 ft.) or less in height, and the 

 white sage (Eurotia lanata), which also occurs on the high table- 



Fig. 5o6c. 



Big Bad Lands of South Dakota, an intervale with well-established vegetation 

 of grasses, shrubs, and trees. (Dept. Geol., Univ. Nebr.) 



lands, while a few bunch-grasses and herbs are rare or occasional 

 wanderers from the outlying districts. 



1052. Alkaline marshes and salt basins. Here and there ii? 

 the salty, alkaline basins, meadows are formed by the sod-grass, 

 Distichlis spicata stricta, and Agropyron pseudorepens. In 

 some of the very salty ponds in the basins, Ruppi? occidentalis, 

 in others the glasswort (Salicornia herbacea) grows, while in the 

 salty soil around the basins certain chenopods (species of Atri- 

 plex), also the bugseed (Corispermum) and other halophytes 

 occur, while farther out are the salty meadows of certain sod-- 

 grasses. Halophytes, of course, are able to flourish in a soil 



