MISC. PUBLICATIOX 162, U. S. DEPT. OF AGRICELTURE 



Tree increasea eech year in 



he'ght and spreaa o^ b-^-^cnes 

 by atíd rng otí rrewg^owTh of' 

 twigS 



Air supp'ies carbón, 

 the pr.ncioal food cf 

 the treeTaken inon 

 andar surface O"? 

 eaves 



L'ghi-and hear 

 "ecessary for 

 cHemlcal charles 



Roo* Tips orreo' haifs faKe 

 i¿p water conTaining aman 

 quanTity o"f mínerals ¡o 

 soluiion. 



Figure 1. — How a tree grows. 



The buds, root tips. and cambium layer are the growing parts of the tree. Water 

 containing a sinall quaiitity of minerals in solution is absorbed by rhe roots, 

 carried up through the sapwood to the leaves and there combined with carbón 

 from the air to inake food. This food is carried by the inner bark to all 

 growing parts of the tree, eren down to the root tips. 



