ROOT SYSTEMS OF MIXED-PRAIRIE SPECIES. 



45 



The vegetation at this station, in the main, belongs to "the bunch- 

 grass association" of Pool (1914), except in the local blowouts and in the 

 valley of the Republican River, where sod-forming vegetation is in 

 control. The following species were examined here: 



Paspalum setaceum. — Tins grass is frequently rather abundant in dry sandy 

 soils. Several bunches, from 1.5 to 8 inches in diameter, were examined. 

 The plants are connected by very thick rhizomes. From the base of the plant 



Fig. 15. — Root system of Paspalum setaceum. 



and from the rhizomes originate great numbers of tough, wiry roots; 40 of 

 these were counted on a single clump only 1.5 inches in diameter. The roots 

 are only about 0.5 mm. in thickness, but because of their characteristic dark- 

 brown color they can be traced with great certainty among the roots of the other 

 species. They fill the soil not only beneath the plant, but on all sides. Some 

 of the roots penetrate vertically downward to maximum depths of 3.8 feet; 

 others pass obliquely downward at all angles, while some run off at a depth of 



