6 A GENERAL VIEW OF PLANTS 



small that they can be seen only with a microscope. Ranging 

 from these very small plants to the largest trees, plants of all 

 sizes and complexity occur about us. The different plant forms 

 differ very much in structure, methods of getting food, and 

 methods of reproduction. The plants which concern us most 

 are those which have flowers. They are known as the Flowering 

 Plants. Most of the cultivated plants and nearly all weeds 

 belong to this group. They are the plants which furnish nearly 

 all of our food and fibers and much of our lumber. Part I of 

 this book is devoted to the study of the Flowering Plants. 



Although the Flowering Plants concern us most, it must not be 

 concluded that the simpler plants are of no importance. The 

 simpler plants, even the microscopic forms, not only help and 

 hinder in the cultivation of the Flowering Plants, but affect us in 

 other ways and must receive consideration. Much of Part II 

 is devoted to the study of them. 



Parts of a Plant. Plants, in no less degree than animals, 

 have definite plans of organization. They too are organisms. 

 The material structure or body of plants, excepting in case of 

 those very simple in structure, consists of parts, called organs, 

 each of which is so constructed as to do a special kind of work, 

 called a function. In the Flowering Plants, the plant body con- 

 sists of roots, stem, leaves, buds, flowers, seeds, and fruit. All of 

 these structures are not present at all times, but unless a Flowering 

 Plant develops all of these organs during its life, its development 

 is considered incomplete. Through the special functions of its 

 organs, the plant is able to exist and reproduce itself. The roots 

 hold the plant to the soil and furnish water and salts; the stem 

 supports the leaves, flowers, and fruit in the air and sunlight; 

 the leaves make food; the buds produce new leaves and flowers; 

 and the flowers, seed, and fruit have to do with the production 

 of new plants. But each organ is also composed of parts and to 

 understand an organ one must understand its special groups of 

 cells, known as tissues, of which the organ is composed. 



Life Cycle of Flowering Plants. A characteristic of living 

 organisms is their ability to use substances as food, grow, and 

 develop. Living organisms are also much influenced by their 

 surroundings. Plants are much influenced by the nature of the 

 soil, air, sunlight, and plants which grow about them. 



To understand a plant one needs to study it in its various 



