234: THE SECOND BOOK OF BOTANY. 



called adventitious roots. The roots of all mono- 

 cotyledons are adventitious. Many dicotyledonous 

 plants produce adventitious roots in the course of 

 growth. 



EXPERIMENTS. Place the branch of a willow with 

 its cut end in the moist ground. It will send out 

 roots, and become an independent plant. 



Detach a slip of geranium from its parent plant 

 and bury its broken end in moist sand. It will take 

 root, and form a perfect plant. 



Observe the roots of Indian-corn, that always 

 arise just above the ground, at the joints, and, grow- 

 ing downward, enter the soil. 



Some plants, as the strawberry, that begin life 

 with true roots, continue it by means of adventitious 

 roots. 



Bend over the young branch of a rose-bush, and 

 bury a portion of it in the soil (layering). It will 

 attach itself by means of adventitious roots, and then 

 you may cut its connection with the parent -bush 

 without harm. 



Adventitious roots are often found on the stem 

 of climbing plants, giving support to them by ad- 

 hering to adjacent objects. 



Only true roots become tap-roots. When the 

 branches of true roots remain small, the central por- 

 tion can thicken ; but, if they are many and vigor- 

 ous, the central portion is lost, and the root becomes 

 fibrous. All the various forms of roots depend upon 

 the amount of the branching and the enlargement of 

 its different portions by deposits of food. 



