CHAPTER II 

 THE GROWTH OF PLANTS 



18. Introduction. It is neitlier tlesirable nor necessary 

 to set down in detail the processes which are involved in 

 the germination of seeds and the growth of plants, the uses 

 of the different elements of plant food, and the effects of til- 

 lage, drainage, and other factors on crop production. The 

 study of growth processes is more properly a part of the work 

 in botanj^ while plant food, cultivation, moisture supply, 

 and other subjects of similar nature may best be discussed 

 along with the study of soils. A brief outline of the way in 

 which plants grow, however, should be of value to the stu- 

 dent or the producer of field crops, in affording a better under- 

 standing of many of the cultural methods and other matters 

 which will be detailed in the discussion of each crop. 



THE SEED AND ITS GERMINATION 



19. What the Seed Is, A seed is a reproductive body 

 produced by flowering plants. It contains an embryo 

 plantlet and usually an amount of plant food, all surrounded 

 by one or more seed coats. Nearly all field crops are grown 

 from seed, though a few, such as potatoes, sweet potatoes, 

 and sugar cane, are grown from divisions of the roots or 

 stalks. The seed consists of a minute plant, the embiyo, 

 and the store of the plant food which surrounds it. This 

 embryo may be seen very readily in a pea or bean. If the 

 seeds of these plants are soaked in water for a few hours, the 

 skin, or outer protective covering, may be removed easily. 

 If the halves are then separated, a minute plantlet will be 

 found adhering to one of them. This is the live portion of 

 the seed, which, under proper conditions, will start into 



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