CHAPTER VII 

 PLANT ORGANS AND ORGANISMS 



An organ is a part of an organism made up of several tissues and 

 capable of performing some special work. 



An organism is a living entity composed of different organs or 

 parts with functions which are separate, but mutually dependent, 

 and essential to the life of the individual. 



The organs of flowering plants are either Vegetative or Reproduc- 

 tive. The vegetative organs of higher plants, are roots, stems, and 

 leaves. They are concerned in the absorption and elaboration of 

 food materials either for tissue-building or storage. 



The reproductive organs of higher plants include those structures 

 whose function it is to continue the species, viz.: the flower, fruit and 

 seed. 



The ripened seed is the product of reproductive processes, and the 

 starting point in the life of all Spermatophytes. The living part of 

 the seed is the embryo, which, when developed, consists of four parts, 

 the caulicle, or rudimentary stem, the lower end of which is the be- 

 ginning of the root, or radicle. At the upper extremity of the stem 

 are one, two, or several thickened bodies, closely resembling leaves, 

 known as cotyledons, and between these a small bud or plumule. 



The function of the cotyledon is to build up nourishment for the 

 rudimentary plantlet until it develops true leaves of its own. 



THE ROOT 



The root is that part of the plant that grows into or toward the 

 .soil, that never develops leaves, rather rarley produces buds, and 

 whose growing apex is covered by a cap. 



The functions of a root are absorption, storage and support. Its 

 principal function is the absorption of nutriment and to this end it 

 generally has branches of rootlets covered with root-hairs which 

 largely increase the absorbing surface. These root-hairs are of 



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