158 



GENERAL BOTANY 



root and in a few weeks may be severed from the propagating 

 leaf as new, independent plants. In the walking fern (Camptoso- 



rus rJdzophyllus) 

 (Fig. 81) new 

 plants are formed 

 from the ends 

 of leaves, which 

 bend downward, 

 touch the soil at 



O/spring 



FIG. 81. The walking fern (Camptosorus) 



their tips, 

 take root. 



ROOTS 



and 



The figure shows how new fern plants take their origin from 

 the tips of leaves 



Many ordinary 

 roots may be 

 made to repro- 

 duce vegetatively in a manner quite similar to that outlined 

 above for the begonia leaf. On the other hand, roots, like stems, 

 may become highly modified for 

 vegetative reproduction. Com- 

 mon examples of this are the 

 roots of the dahlia and of the 

 sweet potato (Fig. 82), which, 

 like the bulb and the tuber, 

 are storehouses of reserve food 

 for the growth of the young 

 plants which spring from them 

 vegetatively. 



In all these cases of vegetar 

 tive reproduction the offspring 

 resemble the parent very closely, 

 since the cells which produce the 



new plants by growth are all FlG ' 82 ' Enlar ed edl ' ble roots of the 



. sweet potato (Ipomoea) 



derived irom a single parent. 



This is often a very distinct advantage to man, since it enables 

 him to perpetuate a favorable set of characters in a new fruit 

 or vegetable much more easily than could be done by sexual 



