ROOT SYSTEMS OF MIXED-PRAIRIE SPECIES. 



53 



figure 22, they are well branched throughout and end in the surface soil. The 

 deeper branches are also wide spreading. Usually the tap dominates through- 

 out. A maximum depth of 5.3 feet was recorded for one of the plants. 

 Another had a tap-root 5 feet long. While this may appear to be a remarkable 

 growth for an annual, it is no greater than that of many crop plants of similar 



Fig. 22. — Widely spreading and deeply penetrating root system of Eriogonum annuum. 



life duration (c/. Chapters VI and VII). Few or no long branches originate 

 below 3 feet. The tips of the deeper roots are poorly branched. The ulti- 

 mate branches are threadlike. The rootlets of the surface laterals are much 

 finer than those of the deeper ones, in fact, the root as a whole has its surface 

 branches much better developed than the deeper ones, although the tap-root 

 is often more prominent than shown in figure 22. This species with its widely 

 spreading surface laterals and moderate depths of penetration is typical of 

 many sandhills plants. 



