CHAPTER XII 
HOW THE ROOT LIFTS WATER IN THE PLANT 
Root pressure in seedlings. To see this we may use 
the seedlings which are growimg vigorously — sun- 
flower, bean, marrow, buckwheat, 
and others. With a sharp knife 
cut off the stem near the upper 
end. In afew minutes a drop of 
water will be seen forming on the 
cut end of the stem. This in- 
creases in size until a large, round 
drop is formed. We know that 
water would not flow upward out 
of the stem unless there was some 
pressure from below. ‘This pres- 
sure comes from the absorptive 
power of the roots. The roots, 
as we have found in our previous 

study, take up water from the soil 
Fic. 123. Drop of water pressed 
out of cut end of stem of 
through the root hairs so forcibly 
sunflower seedling by work of 
as to produce an inside pressure *°* 
which makes the tissue firm. This water is passed 
inward in the root by a similar process until it reaches 
87 
