THE LIVING PLANT 



21 



III. The Leaves . 



IV. Flowers and Fruits 



1. Manufacture food material for use in 



the plant. 



2. Respire. 



3. Transpire. 



4. Shade the stem. 



1. Form seeds in order to produce new 

 plants. 



37. Roots (Figs. 6 and 7). As to shape, roots may be 

 placed in three classes: (1) Tap-roots are thick and tapering. 

 Such roots may be several inches in length, as in the carrot 



and the beet, or may be a number of feet long, as 



in the walnut and pecan. (2) Fascicled roots are 



thick and fleshy, 



but somewhat ir- 



regular in shape, 



as in the sweet 



potato. (3) Fi- 



brous roots are 



long, slender, 



and more or less 



crooked. Such 



roots spring from 



tap-roots and 



fascicled roots, 



or are found on 



plants having neither tap- nor fascicled roots. 

 38. Manner of growth of roots. As the plant 



g rowg) ^ ne roo t s increase in length by the mul- 

 tiplication and enlargement of cells near the tip. As a root 

 pushes through the soil, it is protected by a root-cap consist- 

 ing of a number of modified cells (Fig. 8). Branch roots arise 

 from older roots in a different manner than do the branches of 

 stems. The branch (lateral) roots grow out from the central 

 interior portion of older roots, while the lateral branches of 

 stems arise from buds formed by the outer tissue of the stem. 



FIG. 7. Fascicled roots of the sweet potato. 



FIG. 6. Tap- 

 jarrot. 



