Ch. VIII] COLD TEMPERATE GRASSLAND FORMATIONS 595 



The physiognomy of the western plains is peculiar. The prevailing plant 

 is buffalo-grass (Buchloci dactyloides, Fig. 336), frequently mixed with 

 grama-grass (Bouteloua oligostachya). They form a dense greyish-green 



FIG. 332. Typical natural prairie in Iowa, Cherokee Co. The dark strip in the centre 

 corresponds to a former path. From a photograph by J. M. Coulter. 



sward, two or three inches high. The other plants are scattered here 

 and there in the turf. The Opuntieae are conspicuous, although they 

 lie obliquely and protrude only slightly above the grass. The most 



Q q 2 



