WHAT STRUGGLE FOR EXISTENCE IS 



211 



359. The tree has appropriated the food 



that a large area remains bare of vegetation. 



tion for every inch of its 

 not populated with plants 

 cently been moved. If the 

 his soil frequently, various 

 plants get a foothold, and 

 these plants he calls weeds. 

 Determine how much room 

 an apple tree , or other plan t , 

 occupies : then calculate 

 how much space would be 

 required for all the seed- 

 lings of that tree or plant. 

 The greater the population 

 of any area, the less chance 

 have other plants to gain a 

 foothold. When the wheat 

 completely covers the 

 ground, as in Fig. 357, 

 there are no weeds to be 

 seen. 



352. Plants of different 

 form and liabit may grow 



space, for food 

 and moisture in 

 the soil, for 

 light. We may 

 consider exam- 

 ples in each of 

 these three cate- 

 gories. 



351. If the 

 earth is filled 

 with plants , 



and moisture, so there must be 



sharp competi- 

 surface. If any good soil is 

 it is usually because it has re- 

 farmer does not move or till 



The clematis climbing into the sunlight. 

 Compare Fig. 73. 



