Phloem

A vein in the leaf contains xylem and phloem. Xylem forms hollow, lignin-strengthened tubes that carry water and mineral ions from the roots towards the leaf; the strengthening also helps support the plant. Water reaches leaf cells for photosynthesis.

A plant must move water and dissolved mineral ions from its roots to its leaves and other parts. It must also distribute the sugar made by photosynthesis to parts that need it for growth or storage. These jobs are carried out by two tissues: xylem transports water and mineral ions, while phloem transports sucrose, a sugar made from the products of photosynthesis.

The plant therefore has vascular tissue running through its roots, stems and leaf veins. This contains two specialised transport tissues: xylem and phloem.

Unlike animals, plants do not have blood: they have transport tissues called xylem and phloem. Each is built for a different cargo and job.