Lets talk about the plants vascular system!
There are two main elements: The Xylem and the Phloem.
The Xylem transports water and dissolved minerals from the plants roots to its various organs, terminating at the leaves, where the water is transpired through the plants Stomata into the environment as water vapor. This process is called The Transpirational Stream and is primarily responsible for delivering water and soluble elements to the plants rapidly growing body. The xylem typically resembles many tiny straws packed together into bundles, which run the length of the plant body.
The Phloem delivers organic elements such as sugars, amino acids and small signaling molecules like hormones or mRNA to the plant body. The leaves, which is the primary site for photosynthesis and therefore sugar production, is also from where the phloem flows from. Though this is an oversimplification, it is helpful to imagine the xylem flowing up in the plant body and the phloem flowing down and outward. Tree sap that we all know and love like maple syrup for example, is harvested from the plant's phloem tissue!