42 



THE BOOT 



sap, fasten their roots underground upon the roots of neighboring 

 plants, and rob them of their juices. 



62. Roots as holdfasts. — This 



function comes to be 

 of great importance as 

 the plants become tall 

 and have to stand 

 against the violence of 

 the Avinds. And so 

 the main roots of a 

 tree, spreading abroad 

 underground, corre- 

 spond in girth with 

 the largest of the 

 branch trunks spread 

 in the air above. 

 They increase, like the 

 trunk and limbs, by 

 the annual formation 

 of wood. Yet notwith- 

 standing their great 

 size and strength, 

 every heavy wind 

 storm leaves here and 

 there a tree over- 

 turned. 



63. Roots for climb- 

 ing are well shown by 

 the Trumpet Creeper 

 (Fig. 34). Near the 

 nodes, on the shaded 

 and moister sides of 

 the stem, aerial roots 

 are produced in longi- 

 tudinal rows, and become matted together like felt by 

 means of the numerous root hairs that cover them through- 

 out. As the young stems of the vine push upward close 

 to the face of a wall or building, these webs of roots grow 

 out until they strike the stone, when they flatten out and 



32 



Dodder parasitic on the stem of an herb. 

 Note the absence of leaves (except a 

 few small scales, I), the development of 

 sucking roots, h, and the flower ckister. 

 The plant has no connection with the 

 ground, except in the seedling stage. 



