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CHAPTER X 



HOW PLANTS ARE INFLUENCED BY THEIR 

 SURROUNDINGS 



WE know that the needs of the plant are the same as 

 ours; food, water, light, air, and warmth. If a green 

 plant lacks any of these it dies. Too much of any one 

 of these is as bad as too little. What the plant needs is 

 the golden mean. Where the plant finds this it grows 

 well. But there are many places where it must grow 

 under unfavorable conditions. How the plant meets 

 such conditions is worth studying. 



Water. A potato contains sufficient water to sprout 

 by itself, even when kept rather dry; if a potato which 

 has just started to sprout is placed where it is not ex- 

 posed to direct sunlight, it will continue to grow while 

 lying on a dry table top and finally come to look like 

 figure 63. 



Its growth has been very slow (the ordinary potato 

 plant of which a branch is shown in figure 64, grows a 

 hundred times larger in the same length of time). Its 

 branches are thick and clumsy. It bears no leaves, 

 but their work is performed by the green rind of the 

 stem and branches. 



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