CHAPTER VII. 
PLANT NEEDS. 
LANTS need water, air, food, light and 
warmth just as animals do, and it is wonder- 
ful to study the shifts and contrivances to 
which they resort to get these, and also to pro- 
tect themselves against too much of any of 
them. If the plant were not able to change 
itself to suit the conditions, it would often die 
where now it fights successfully. 
Nothing affects the plant like the water 
supply; the size of every part of the plant is 
increased by plenty of water. It not only helps 
the growth of flowers and fruits, but it even 
changes the character of the plant. In a moist 
air, cactus will put out leaf-like organs, gorse 
will grow leaves instead of thorns; while where 
the water supply is very scanty, the potato will 
put forth no leaves, but will become like a 
cactus. 
Yet plants do not grow in soil that is too wet, 
because they need air, and too much water 
suffocates the roots. By proper irigation— 
which means giving just the right supply of 
water—both the quantity and quality of the 
crop can be improved. 
While plants need light, all varieties do not 
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