XIV 
ROOTS ARE PUMPS 
I SN’T IT ODD that the roots of trees are able to draw 
water out of the ground as easily as does the pump 
on the back porch! 
The average-sized tree may use as much water every 
day as the average-sized family. The roots supply it. 
They often perform a task which is different from that 
of the pump, for they get this water from regions where 
there seems to be none. They, unlike the pump, do not 
need to reach down into some stream flow. They can 
get their barrels of water from ordinary soil, where it 
exists only in the form of dampness. 
The root, working underground as it does, is a rather 
remarkable instrument. In the first place, it must drive 
itself deeply into the earth. It has a thimble on the end 
which helps it do this. Having driven itself into the 
ground, it proceeds to grow, pushing outward with great 
force as it does so. Along the streets of almost any city 
where there are trees one sees places where a root has run 
under a sidewalk and in growing has lifted that sidewalk 
quite above the level. 
The ends of the harder roots are able to pump water if 
they happen to reach an actual stream of it, but the task 
of gathering it under ordinary conditions is assigned to a 
quite different group. Nearly all the larger roots send 
out near their ends great numbers of tiny threads known 
as root hairs. These forage for water where there seems 
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