CHAPTER X 

 REPRODUCTION 



Thus far we have studied the plant body as an individual, in 

 which roots, stems, and leaves develop characteristically and 

 function in such a way that the successful existence of the plant 

 is assured. The individual ultimately disappears, however, and 

 it is obviously necessary that if the species to which it belongs is 

 to survive and maintain itself, some means must be provided for 

 insuring a constant succession of new individuals by transmitting 

 the life of one generation to another. This is accomplished by the 

 process which we know as reproduction, whereby the plant, by 

 one means or another, produces a group of offspring. The 

 structures and functions of all plants may thus be divided into 

 two rather sharply marked groups: The vegetative, centering 

 around the root, stem, and leaf, which are concerned primarily 

 with the life of the individual plant; and the reproductive, center- 

 ing around the flower and fruit, which are concerned primarily 

 with the maintenance of the species. It is the latter group which 

 we shall now discuss. 



There are two main types of reproduction, markedly different 

 from one another. These are asexual or vegetative reproduction, 

 in which portions of the body of the parent become detached from 

 it and are set apart as new individuals; and sexual reproduction, 

 where there is a union between two speciahzed reproductive cells, 

 from which union a new individual arises. 



Asexual Reproduction. — The simplest type of asexual repro- 

 duction consists in the division of the parent plant into two or 

 more parts, each of which becomes independent. It is a character- 

 istic property of most plants that a small portion of the body, 

 (particularly if it includes a bud) when removed and placed under 

 favorable conditions, will replace the missing parts and develop 

 into a new individual. This readiness for multiplication is made 

 use of extensively in the various arts of plant propagation, by 

 which new individuals are produced through cuttings and like 

 processes. In a somewhat similar manner, a bud or twig from 



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