CHAPTER VII. 



PLANT NEEDS. 



PLANTS 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 irrigation — 

 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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