Xylem is a complex tissue found in vascular plants that transports water and nutrients from the roots to the stems and leaves. The constituents of xylem include four types of cells: tracheids, vessels, xylem fibers, and xylem parenchyma.
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Tracheids: These are elongated cells with tapered ends that transport water and minerals through pits in their walls.
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Vessels: These are shorter and wider than tracheids and are composed of vessel segments or vessel elements. They are connected together into long tubes that are called vessels. Vessel elements form one continuous vessel with perforated plates which connects all vessel elements.
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Xylem fibers: These are dead cells with lignified walls and a central lumen. They help in the transportation of water and provide mechanical support.
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Xylem parenchyma: These are living cells that help to make the softest part of the plant and long fibers which support the plant.
Xylem can be found in the non-woody parts of woody plants, in non-woody plants, and in secondary xylem laid down by a meristem called the vascular cambium in woody plants.
