80 



ROOT DEVELOPMENT IN THE GRASSLAND FORMATION. 



parallel with the soil surface, but more often obliquely downward to distances 

 of 1 to 1.2 feet before turning directly downward. These, with the more or 

 less vertically penetrating roots, form a dense sod to a depth of about 2.7 feet. 

 The surface soil layer is especially well occupied with dense masses of finely 

 branched rootlets, but branching continues to the very root-tips. Many of 

 these laterals are over 2.5 feet long and are rebranched to the third and fourth 

 order. The root-ends formed a finely branched network or mat of roots 0.2 to 

 0.3 foot wide and about 1.5 feet long in the deeper soil, the branching mostly 

 being confined to the one plane in the jointed subsoil. 



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Fig. 28. — Root system of Andropogon scoparius excavated in the sandhills. 



At Haigler, Nebraska, the plants were excavated in the sandhills. Three 

 large bunches growing on a partly covered hillside were examined. Roots 

 beneath the clumps were not at all abundant. Most of the roots ran off 

 rather parallel with the soil surface or slightly obliquely for long distances, 

 where they ended or finally turned downward. Numerous roots were traced 

 to their enlarged, unbranched, growing-tips at a horizontal distance of over 2 

 feet from the base of the clump and in the first 0.8 foot of sand. Others are 

 shorter and shallower. Still others turned more obliquely downward and 

 extended well in to the third foot of soil. A few reached maximum depths of 

 3.5 feet, but they were rare below 3 feet. Branching was profuse, as already 

 described. Figure 28 shows one of the plants excavated at this place. Its 

 root habit reminds one strongly of that of Aristida purpurea when growing in 

 the sand (p. 84) . The enlargement of some of the root-ends was a frequently 

 observed feature of several species of sandhills plants. The tip often rapidly 

 and rather abruptly increases in size from 2 to 5 times its original diameter and 



