Heartwood gives strength. 
Sapwood carries sap from 
roots. 
Cambium builds cells. 
Inner bark carries prepared 
food from leaves to Cam- 
bium layer, etc. 
Outer bark protects tree. 
ie 
Soil, source of much of 
the tree's food and air. 
Mulch protects the surface 
from drying. 
Decomposing layer. 
Subsoil, the deep roots find 
water and anchor the tree 
firmly in place. 
oe Insect passages. 
The above chart is based on U. S. Department of 
Agriculture Soil Service Chart of idealized tree. 
Buds, root tips, and cambium layer are the growing 
parts of the tree. Water with minerals is absorbed 
by the roots, carried via sapwood to the leaves, and 
combined with carbon from air to make food. This 
food is carried by the inner bar to all growing parts 
of the tree, even to root-tips. 
in each leaf during the daylight hours from early 
spring when the leaves appear to late summer or 
early fall. 
THE DISTRIBUTION 
The solution of water and this newly manu- 
factured food, glucose, now enters the other com- 
ponents of the vascular system, the phloem tubes. 
These lie outside the wood and the cambium layer 
and directly under the non-living bark. Through 
the phloem the glucose solution is conducted to 
all other parts of the tree, to newly-forming 
leaves, to the twigs, the branches, the trunk and 
the roots. It is used by these parts to provide 
energy for the continuance of life, to be combined 
with the soil salts to make new compounds such 
as fats and proteins, or to be converted into starch. 
5 
