86 



THE ROOT. 



aerial rootlets strike from the horizontal branches of the tree, often 

 at a great height, at first swinging free iii the air, but finally reach- 

 ing and establishing 

 themselves in the 

 ground, where they 

 increase in diame- 

 ter and form acces- 

 sory trunks, sur- 

 rounding the origi- 

 nal boll and sup- 

 porting the wide- 

 spread canopy of 

 branches and foh- 

 age. Very similar 

 is the economy of 

 the Mangrove (Fig. 

 141), which forms 

 impenetrable thick- 

 ets on low and mud- 

 dy sea-shores in the 

 tropics, and even 

 occurs on the coast 

 of Florida and Lou- 

 isiana. Here aerial roots spring not only from the main trunk, as 

 in the Pandanus, but also from the branchlets, as in the Banyan. 



FIG. 140. The Pandanus, or Screw-Pine; with, 141, a MangrOYe-tree (Rhizophora Mangle> 

 FIG. 142. The Banyan-tree, or Indian Fig (FicuB Indica). 



