Tree sap is made of water with sugars and mineral salts dissolved in it. Different species of trees have different sap profiles. Maple sap is edible, but the sap produced by other trees is inedible or even toxic.
Botanists divide sap into two types: phloem sap and xylem sap. Phloem sap travels from sugar-rich areas of the tree to areas that are sugar-poor. In practice, this means that the sap flows from the leaves to the trunk and roots. Xylem sap, on the other hand, is rich in nutrients from the outside environment and travels upward from roots to leaves.