ROOTS 



31 



air-plants are grown in greenhouses. In such plants as the 

 ivy (Fig. 13) the aerial roots (which are also adventitious) 

 hold the plant to the wall or other surface up which it climbs. 

 In the Indian corn roots are sent out from nodes at some 

 distance above the ground and finally descend untU they 





Fig. 13. Aerial Adventitious Roots of the Ivy. 



enter the ground. They serve botli to anchor the corn- 

 stalk so as to enable it to resist the wind and to supply 

 additional water to the plant.^ They often produce no 

 rootlets until they reach the ground. 



41. Water-Roots. — ]\Iany plants, such as the willow, 

 readily adapt their roots to live either in earth or in water, 

 and some, like the little floating duckweed, regularly produce 



1 Specimens of the lower part of the cornstalk, with ordinary roots and 

 aerial root's, should be dried and kept for class study. 



