GROWTH AND WORK OF PLANTS 



whclc. These principal parts may be stated as follows: First, 

 the roots for fixing the plant to the soil and for the absorption of 

 water and liquid food; second, the stem (or shoot, with its branches) 

 as a means of support for the other parts and as a means of 

 communication between the parts; third, the green leaves in 



which certain kinds of food 

 substances are made; fourth, 

 the flowers, which are particular 

 clusters of leaf-like parts work- 

 ing together for the production 

 of fruit and seed in order that 

 new individual plants may be 

 formed. 



3. The minute structure of 

 plants. The parts of plants, as 

 well as of animals, possess a very 

 complex structure. The units 

 of this structure are minute por- 

 tions which, in plants, usually 

 are bounded by distinct walls. 

 These units are microscopic in 

 size. A single one resembles a 

 very minute box or cell, and for 

 this reason they have been called 

 cells. Plant cells vary greatly in 

 form and in size. In the higher 

 plants they are united in groups 

 or masses which are often very 



characteristic. Cells united together form a tissue. Tissues 

 vary according to the form, arrangement and work of the cells. 

 In the higher plants, every one of its parts (root, stem, leaf, 

 etc.) is made up of several different kinds of tissue systems 

 (See figs. 39, 40, 60, 75), each system performing its particular 

 kind of work. 



4. Division of labor in the plant. The plant might be 

 compared to a large industrial community composed of persons 





Fig. i. 



Diagram of plant showing the principal 

 parts. R, root;, S, stem; L, leaf. Black 

 lines within show the vascular system for 

 the conduction of water and mineral foods 

 from the soil. After Sachs. 



