What Is Tree Sap Made of?
Like all other plants, trees transport water and minerals from roots to shoots and sugar from the leaves to other parts of the tree. Fluids carrying nutrients and sugars in the tree are called sap. Does this Spark an idea?
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Types
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There are two main types of sap: xylem sap and phloem sap. Xylem sap flows up from roots to shoots through the xylem tissue in the wood of the tree trunk, while phloem sap flows down from the leaves through the innermost layer of the bark.
Function
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Xylem sap is composed of water, minerals and nutrients taken up through the roots; it is mostly water with some dissolved substances. Phloem sap is also mostly water, but unlike xylem sap phloem sap is rich in sugar produced by the leaves. The phloem carries these sugars to parts of the plant that cannot photosynthesize, like the roots. Phloem also contains some plant proteins and plant hormones that act as signals from one part of the plant to another.
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Fun Fact
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Since the phloem tissue is the innermost layer of the bark -- and since the roots and many other parts of the plant cannot survive without sugars from the leaves -- stripping off the bark in a circle all the way around the tree will kill it, because phloem sap can no longer make its way to the parts of the tree beneath the gap.
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References
- Photo Credit Green tree with red tree image by Lee Mann from Fotolia.com
