468 Report or trHE HorricutturaL DEPARTMENT OF THE 
Shape of root systems.—But by far the most remarkable dif- 
ference in the root systems of the trees in the two plats is in 
the shape. The roots of the tilled trees spread out much as 
do the branches, with a sweep not much -greater than the 
branches. The circumference of the root system of such a 
tree is nearly circular, with the feeding roots in a plane of six 
or eight inches. But the circumference of the root system 
of the trees in sod is very irregular with many offshoots in 
this direction and that, and with much more unevenness as to 
depth.’ The great irregularity in the root system of these trees 
must be due to some force or forces which attracts them from 
the normal. There is a reaching out of a part of the roots in 
response to a demand for more moisture, food, or air, or all 
of these, or to escape some evil effect of the grass roots. This 
unevenness of growth is shown in Plate XXTX where the roots 
of a tree in sod are shown in the adjoining tilled land at a dis. 
tance of from 20 to 30 feet from the tree; again in Plate XXX 
a large root and its branches, rootlets, and roothairs are shown 
passing under a stone wall into a lane to a distance of from 30 
to 40 feet. These abnormalities were not to be found in the 
root system of the tilled trees. 
Quantity of roots.—There is no fair way of comparing the 
size, quantity or bulk of the roots of the trees in the two plats. 
To obtain such data at all accurately would mean the removal 
of some of the trees and even then countless numbers of root- 
lets would be destroyed. It is not possible to remove a given 
bulk of earth from the two plats and so measure the quantity 
of functioning roots with accuracy; for, in the sod the masses 
of roots have been accumulating for six years while in the 
tilled land there has been a yearly pruning by the plow and 
the consequent formation of new roots. Were the data as to 
quantity obtainable, it would be difficult to draw conclusions 
from them as almost nothing is known of how much work roots 
ean do. Thus a small root system may do quite as much work 
in one soil or environment as a large root system would in 
another; so, too a mass of roots may be Jarge and bulky with 
functionless roots while a smaller one may contain only live 
