xylem and phloem

Xylem and phloem make up the big transportation system of vascular plants. As you get bigger, it is more difficult to transport nutrients, water, and sugars around your body. You have a circulatory system if you want to keep growing. As plants evolved to be larger, they also developed their own kind of circulatory systems. The main parts you will hear a lot about are called xylem and phloem.

It all starts with a top and a bottom. Logically, it makes sense. Trees and other vascular plants have a top and a bottom. The top has a trunk, branches, leaves, or needles. The bottom is a system of roots. Each needs the other to survive. The roots hold the plant steady and grab moisture and nutrients from the soil. The top is in the light, conducting photosynthesis and helping the plant reproduce. You have to connect the two parts. That's where xylem and phloem come in.

Xylem caries water and disolved nutrients from the roots throughout the plant.

Phloem carries/ distributes the products of photosynthesis (mainly from the leaves) to the rest of the plants.

Xylem is the upward conduction of water while phloem is the upward and downward conduction of food and minerals.

	Phloem	Xylem
Function:	Transportation of food and nutrients from leaves to storage organs and growing parts of plant.	Water and mineral transport from roots to aerial parts of the plant.
Movement:	Bidirectional (Moves up or down the plant's stem from "source to sink")	Unidirectional (Moves up the plant's stem)
Occurrence:	Roots, stems and leaves	Roots, stems and leaves
Additional Functions:	Forms vascular bundles with xylem	Forms vascular bundles with phloem and gives mechanical strength to plant due to presence of lignified cells.
Structure:	Tubular with soft walled cells	Tubular with hard walled cells
Elements:	Sieve tubes, companion cells, phloem parenchyma, bast fibers, intermediary cells, two tube flow	Tracheids, vessel elements, xylem parenchyma, xylem sclerenchyma
Nature of tissue:	Living tissue	Non living tissue at maturity

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