Xylem is a specialized tissue in vascular plants that transports water and nutrients from the roots to the stems and leaves. The basic function of xylem is to transport water, but it also transports nutrients. Water with minerals and occasional organic molecules supplied by the root tissue move up in the vessels and tracheids of the xylem. Minerals enter the root by active transport into the symplast of epidermal cells and move toward and into the stele through the plasmodesmata connecting the cells. They enter the water in the xylem from the cells of the pericycle (as well as of parenchyma cells surrounding the xylem) through specialized transmembrane channels. At any level, the water can leave the xylem and pass laterally to supply the needs of other tissues. At the leaves, the xylem passes into the petiole and then into the veins of the leaf. Water leaves the finest veins and enters the cells of the spongy and palisade layers. Here some of the water may be used in metabolism, but most is lost in transpiration.

In summary, xylem transports water and nutrients from the roots to the stems and leaves of vascular plants.