20 HORTICULTURE FOR SCHOOLS 



35. Plastids are small bodies contained within the cyto- 

 plasm. They possess the power of growth and multiplication 

 by division. There are three types. The leucoplasts are 

 colorless. Their function is to change soluble sugars into 



insoluble starch grains which 

 they store within themselves. 

 The chloroplasts are green in 

 color and are necessary in 

 the manufacture (photosyn- 

 thesis) of plant-food. The 

 chromoplasts are red, yellow, 

 or o^nge in color and some- 

 times crystalline in form (Fig. 

 5) . The colors of many flowers 



tO 



F.o.S.-Chroroopastsofvariousshapes: 



presence. 



36. Functions of plant parts. As has been stated, the 

 parts of the plant consist of a large number of cells, many of 

 which are highly specialized to perform certain definite kinds 

 of work, but all of which work together for the good of the 

 plant. Each part of the plant performs certain functions. 

 For the convenience of the student, the uses of the roots, 

 stems, leaves, flowers, and fruits are summarized in the 

 following : 



FUNCTIONS OF PLANT PARTS 



I. The Roots . . 



II. The Stem . 



1. Absorb water and food materials. 



2. Transport water and food materials. 



3. Store food material. 



4. Fix the plant in a definite place and 



position. 



1. Transports water and food materials. 



2. Holds the leaves up into the sunshine 



and air. 



3. Stores food material in many cases. 



