Phloem is the living tissue in vascular plants that is responsible for the transportation of organic food materials such as sucrose from the leaf to the rest of the plant. The phloem has four major parts; the sieve tube, companion cells, phloem fibers, and parenchyma. Phloem is classified as primary or secondary phloem based on the stage of its growth. The primary phloem comes from the primary meristem when the plant is developing, and the secondary phloem comes from the secondary meristems of a plant. The picture above is of a vascular plant which contains phloem.