CHAPTER SEVEN 
‘WATER AND THE PLANT 
The thirsty Earth soaks up the rain, 
And drinks and gaps for drink again ; 
The plants suck in the Earth, and are 
With constant drinking fresh and fair. 
ABRAHAM COWLEY 
Water forms a large part of a living plant. Lettuce 
and various toot crops, for example, are nine-tenths 
water. The living matter of the cells is bathed in it, 
and the whole structure of a plant, from the finest 
rootlets to the most delicate tissues in the leaves, is 
more or less filled with it. For good growth, garden 
plants require large amounts of water, and the gardener 
is interested in knowing how this may be provided for 
them. 
How water is used by a plant. All the various mineral 
substances needed by the plant can be taken in only 
when they are dissolved in water. They are all obtained 
from the water that is in the soil. Furthermore, every- 
thing that is moved about inside the plant is carried 
in water; only minerals and foods that are dissolved 
in water can pass from one part of the plant to 
another. 
Great quantities of water are evaporated (transpired) 
from the leaves of plants. For every pound of dry 
material in a mature plant, 5oo pounds of water have 
passed through that plant during its life. An acre of 
thrifty vegetables in a single season uses 1000 tons of 
water, which is equal to about 9 inches of rainfall over 
the acre. A large sunflower in a single day of mid- 
summer transpires more than a pint of water. 
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