Xylem:

-Primary function is to transport water and mineral salts from the roots to the upper parts of the plant, including the leaves and stems.

-Composed of dead cells called vessel elements or tracheids. These cells have lignin-reinforced cell walls, which provide structural support and enable the efficient movement of water through the xylem.

-Water is mainly transported through the cohesion-tension mechanism, which involves the attraction between water molecules and the hydrophilic xylem cell walls, as well as the negative pressure generated due to transpiration from the leaves.

-Xylem vessels also facilitate the transport of dissolved mineral nutrients and other substances, such as hormones, from the roots to the rest of the plant.

-Additionally, xylem tissue contributes to the structural strength of the plant, particularly in woody plants, due to the lignification of its cell walls.

Pholem:

-Primary function is to transport organic compounds, mainly sucrose (a sugar) produced by photosynthesis in the leaves, to other parts of the plant where they are needed for growth, storage, and energy.

-Composed of living cells called sieve tube elements and companion cells. Sieve tube elements are connected to each other through sieve plates and lack a nucleus and most organelles, allowing for efficient transport of substances.

-Organic compounds, such as sucrose and amino acids, are actively transported through the phloem via a process called translocation, where the movement of substances is driven by differences in osmotic pressure and energy from ATP.

-The companion cells play a crucial role in maintaining the health of the sieve tube elements and regulating translocation by providing metabolic support and controlling the opening and closing of sieve pores.

-Phloem transports carbohydrates, proteins, and other organic compounds to support growth, flowering, fruit development, and storage of reserves in different plant tissues.