PLANT SUCCESSIOlSr AND RANGE MANAGEMENT. 



25 



and rubberweed may be classed as intermediate in the elongation oif 

 their roots between small mountain porcupine grass on the one hand 

 and yellow brush on the other. Yarrow, sweet sage, and blue fox- 

 glove, James' chickweed, scarlet gilia, and the annuals, being less 

 deeply rooted than small mountain porcupine grass, may be classed 



as superficial feeders. This wide variation in the extension of the 

 roots is accounted for, of course, by the uniformity in the distribu- 

 tion of the water in the soil from the surface to the extreme depth 

 to which the roots extend. The roots of the numerous species consti- 

 tuting this consociation are so evenly distributed through the soil 



