Plant Tissues and Their Functions
Learn the main plant tissues and their functions, including epidermal, palisade, spongy mesophyll, xylem, phloem and meristem tissue.
Plant tissues are groups of cells with similar structures that work together to perform a particular function. The main plant tissues you need to know are epidermal tissue, palisade mesophyll, spongy mesophyll, xylem, phloem and meristem tissue.
Main plant tissues
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Epidermal tissue covers the plant and protects it. In leaves, it is usually thin and transparent so that light can reach the photosynthetic cells beneath it. A waxy cuticle helps to reduce water loss.
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Palisade mesophyll is found near the upper surface of a leaf. Its cells contain many chloroplasts, so this is where most photosynthesis takes place.
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Spongy mesophyll contains many air spaces. These allow carbon dioxide and oxygen to diffuse efficiently between the leaf cells and the stomata.
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Xylem tissue transports water and mineral ions from the roots to the stems and leaves. Xylem vessels are hollow tubes strengthened by lignin, which also helps support the plant.
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Phloem tissue transports dissolved sugars from the leaves to other parts of the plant, where they are used immediately or stored. This movement is called translocation.
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Meristem tissue is found at the growing tips of roots and shoots. Its cells can divide and differentiate into other types of plant cell, allowing the plant to grow throughout its life.
Stomata are pores, mainly in the lower epidermis of leaves. Each stoma is surrounded by guard cells, which control gas exchange and water loss by opening or closing the pore.
Example
A palisade cell has many chloroplasts because it needs to absorb plenty of light for photosynthesis. This shows how a tissue’s structure is related to its function.
Common exam mistake
Do not confuse xylem with phloem. Xylem carries water and mineral ions from the roots, while phloem carries dissolved sugars from the leaves.
This answer assumes AQA GCSE Biology separate science at Higher tier, although the plant-tissue content described here is assessed at both Foundation and Higher tier and is shared with Combined Science.
