chlorenchyma

Chlorenchyma is a type of plant tissue composed of living parenchyma cells that contain chloroplasts and are specialized for photosynthesis. It represents the green, photosynthetic portion of the ground tissue in many plant organs and is a key component of leaf mesophyll.

Structure and distribution: Chlorenchyma cells are thin-walled, loosely arranged parenchyma with abundant chloroplasts. They are often elongated or isodiametric and can be organized as the palisade and spongy layers of the leaf mesophyll, or occur in the cortex and green stems. In aquatic or emergent plants, chlorenchyma may lie just beneath the epidermis and contribute to underwater photosynthesis. The tissue may be interspersed with intercellular spaces that aid gas exchange.

Function: The primary role of chlorenchyma is photosynthesis. The chloroplast-rich cells capture light energy and drive the synthesis of sugars from carbon dioxide and water. Chlorenchyma can also store photosynthates and participate in gas exchange through intercellular spaces, supporting both light capture and carbohydrate production in green tissues.

Development and variation: Chlorenchyma develops from undifferentiated parenchyma as leaves and green stems mature. Its degree of chloroplast content, cell size, and arrangement varies with species, light conditions, and organ position, with sunlit tissues typically showing more densely organized chlorenchyma to maximize photosynthetic efficiency.

See also: mesophyll, parenchyma, photosynthesis.