Where Palisade Mesophyll is Found
The palisade mesophyll is a layer of plant cells situated within the leaf, positioned directly beneath the upper epidermis. This arrangement places it in the upper region of the mesophyll, the internal tissue primarily responsible for photosynthesis. It lies above the spongy mesophyll, which has a more irregular and loosely arranged cell structure. This specific location ensures the palisade mesophyll is optimally positioned to receive incoming sunlight.
Structure of Palisade Mesophyll Cells
Palisade mesophyll cells exhibit distinctive anatomical features, contributing to their specialized function. They are typically elongated and columnar in shape, often described as cylindrical, and are tightly packed together in one or more layers. This tight packing allows for maximum light absorption.
A defining characteristic is the abundance of chloroplasts within these cells, which are the sites of photosynthesis. These chloroplasts are often concentrated in the upper part of the cell or positioned along the cell walls, optimizing light capture. Palisade cells also contain a large central vacuole, which pushes the chloroplasts towards the cell’s periphery, further enhancing light exposure. A thin layer of cytoplasm surrounds the vacuole and contains other organelles.
The Primary Role of Palisade Mesophyll
The primary role of the palisade mesophyll is to conduct the majority of photosynthesis within the leaf. This process converts light energy into chemical energy, producing glucose for the plant. The structural features of palisade cells are specifically adapted to maximize the efficiency of light absorption and the photosynthetic process.
Their elongated, columnar shape and tight arrangement allow them to capture a high amount of incoming sunlight that penetrates the upper epidermis. The high concentration of chloroplasts within these cells, particularly their strategic positioning, ensures efficient light capture for photosynthesis. These cells absorb blue and red wavelengths of light, which are crucial for driving the photosynthetic reactions.
Furthermore, while tightly packed, there are small intercellular spaces between palisade cells and with the underlying spongy mesophyll, facilitating the necessary gas exchange. Carbon dioxide from the atmosphere diffuses into these cells for photosynthesis, and oxygen, a byproduct, is released. This combination of structure and location makes the palisade mesophyll the primary photosynthetic tissue in many plants.