176 



verted into a thin layer of leaf-mold. The deeper roots of the 

 trees penetrate to, and draw a portion of their inorganic food 

 from, the lower strata of sand, and much of this is returned to 

 the soil in the dead leaves, thus restoring to the upper layers 

 of the sand some of the food matter leached out by years of 

 rainfall. 



TABLE XL CLEARING IN BLACK-JACK ASSOCIATION. 



Other species: Teucrium canadense, Eu- 

 phorbia corollata. 



TABLE XII. NATURAL OPENING IN BLACK-JACK 

 ASSOCIATION. 



Other species : Gallirrhoe triangulata, Ca- 

 rex gravida. 



* See p. 159. 



