- Phloem is a tubular structure found in the roots, stems and leaves, which transports food and nutrients throughout the plant. Since plants derive most of their food and nutrients from sunlight, which is most abundant in the upper portions of the plant, phloem transports food down through the plant. Food and nutrients can travel in two directions through the phloem.
- Xylem is also found throughout the roots, stems and leaves of the plant. Xylem is wholly dedicated to transporting water throughout the entirety of the plant, the majority of which comes from the bottom of the plant at the roots. Xylem transports water in only one direction: up to the top.
- While xylem and phloem are both tubular structures that run throughout the plant, with the phloem toward the outside while xylem is more interior, the two are different in how they function throughout the lifespan of the plant. As plants grow and mature the phloem remains as a living tissue with soft cell walls. Once the plant matures, however, the xylem becomes a nonliving tissue with hardened cell walls.
- While both phloem and xylem are present through the entire plant, and form bonds with each other, only xylem has the secondary function of providing structural support within the plant. As a nonliving tissue, with a hardened cell wall structure, the xylem helps to provide strength and support to the plant itself. As phloem is a living, soft celled tissue, it is too malleable to provide support.
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