Palisade mesophyll
/ˈpælɪˌseɪd ˈmɛsəˌfɪl/
Definition
Palisade mesophyll is a layer of tightly packed, elongated cells inside a leaf, usually just beneath the upper epidermis. It is a plant tissue specialized for photosynthesis, with many chloroplasts, the structures that capture light. Unlike the looser spongy mesophyll below, its cells are arranged upright and close together, helping absorb strong light efficiently in many broad leaves.
Function in Plants
- Main site of photosynthesis: Palisade mesophyll contains many chloroplasts, so it captures much of the light entering a leaf and produces a large share of the sugars that fuel growth and repair.
- Position under the upper surface: Its placement just below the upper epidermis helps the leaf use incoming light efficiently before it is scattered or absorbed by deeper tissues.
- Link to leaf adaptation: Sun leaves often develop a thicker or more layered palisade mesophyll than shade leaves, which helps plants handle brighter conditions and maintain photosynthetic output.
- Coordination with spongy tissue: Palisade mesophyll works with the spongy mesophyll below it, where larger air spaces support carbon dioxide movement needed for photosynthesis.
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