mesophyll

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Orange and red leaves on a tree.

Explore the anatomy of a plant's mesophyll to understand how chlorophyll generates a green appearance

The Function and Structure of Chloroplasts

mesophyll

plant anatomy

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June 30, 2026

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leaf mesophyll — leaf mesophyll Leaf mesophyll composed of parenchyma tissue. The elongated palisade parenchyma contains the largest number of chloroplasts per cell and is the primary site of photosynthesis in many plants. The irregular spongy parenchyma also contains chloroplasts and facilitates the passage of gases through its many intercellular spaces.

Mesophyll is the inner tissue of a foliage leaf, located between the upper and lower epidermal layers. This tissue is a type of parenchyma, which consists of living, adaptable cells involved in vital plant functions.12

The mesophyll is actively engaged in photosynthesis due to its high concentration of chloroplasts. A key component of the mesophyll is the palisade layer, which is rich in chloroplasts and found directly beneath the upper epidermis. This specialized layer plays a crucial role in capturing sunlight for photosynthesis. Parenchyma tissue, including mesophyll, can be densely packed or have spaces between cells.23

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parenchyma
mesophyll (internal layers) of leaves and the cortex (outer layers) and pith (innermost layers) of stems and roots; it also forms the soft tissues of fruits. Cells of this type are also contained in xylem and phloem
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mesophyll (internal layers) of leaves and the cortex (outer layers) and pith (innermost layers) of stems and roots; it also forms the soft tissues of fruits. Cells of this type are also contained in xylem and phloem
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photosynthesis
Carbon fixation in C4 plants
…photosynthetic functions are divided between mesophyll and bundle-sheath leaf cells, meaning there is a spatial separation of carbon fixation. Such plants use a pathway known as C₄ carbon fixation, which modifies and expands on the Calvin-Benson cycle of C₃ plants.
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…photosynthetic functions are divided between mesophyll and bundle-sheath leaf cells, meaning there is a spatial separation of carbon fixation. Such plants use a pathway known as C₄ carbon fixation, which modifies and expands on the Calvin-Benson cycle of C₃ plants.
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tree
Leaf adaptations
…present within the loosely packed mesophyll, and the cuticle is reduced, as are the number and frequency of veins. The stomates are larger but less closely spaced and either level with the leaf surface or elevated above it. The amount of fibrous tissue is reduced, and the hypodermis is absent.…
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…present within the loosely packed mesophyll, and the cuticle is reduced, as are the number and frequency of veins. The stomates are larger but less closely spaced and either level with the leaf surface or elevated above it. The amount of fibrous tissue is reduced, and the hypodermis is absent.…
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