How sap circulates in a tree.

1. Roots suck up minerals and water in a liquid called "Crude Sap".
2. "Crude Sap" rises up the tree through the Sapwood to the leaves.
3. Carbon Dioxide in the air and the sunlight shining on the green chlorophyll in the leaves, change the minerials & water of the "Crude Sap" into a sugary liquid called "Elaborated Sap". This is the tree's food.
4. "Elaborated Sap" goes down the tree through the Bast.
5. "Elaborated Sap" passes from the Bast into the Cambium Layer which is where growth takes place.
6. Medullary Rays allow some of the "Elaborated Sap" to travel inside the tree to convert Sapwood into Heartwood.