The cells are more or less isodiametric. Typical parenchymatous cells are oval, spherical or polygonal in shape.
Their walls are thin and made of cellulose. Young cells are loosely packed with intercellular spaces. The cells have active protoplast having power of growth and division.
They may contain leucoplasts or sometimes chloroplasts. The cells contain vacuolated cytoplasm with a distinct nucleus.
They occur universally in all plants in the softer parts like cortex; pith, mesophyll of leaves, fleshy parts of succulents, pulp of fleshy fruits etc.
ADVERTISEMENTS:
Type of parenchyma:
(i) Normal type: They are isodiametric with intercellular spaces. They form cortex, pith etc.
(ii) Chlorenchyma: These are the parenchyma containing chloroplasts.
(iii) Aerenchyma: Parenchymatous cells with well developed air cavities forming a connected system throughout the entire plant. They provide buoyancy to the floating hydrophytes and also help in gaseous exchange.
ADVERTISEMENTS:
(iv) Idioblast: These are the parenchyma which produce and store oil, tannins, calcium oxalate in their vacuoles or cytoplasm.
(v) Prosenchyma: These are thick and elongated cells providing mechanical support to the plants.
(vi) Accessory parenchyma: parenchymatons cells which become meristematic and help in repairing wound.
Function of paranchyma:
ADVERTISEMENTS:
Its function is mainly storage of food, water and mucilage. It helps in photo synthesis; provide buoyancy to plants, helps in gaseous exchange and wound healing and regeneration by cell division.