The parenchyma tissue is composed of living cells which are variable in thin morphology and physiology but generally having thin wall and a polyhedral shape and concern with vegetative activities of the plant.
They have inter cellular spaces between them.
They act as storage for food and water. Types of Parenchyma : Aerenchyma :
In hydrophytes, the intercellular space between cells become wide & filled with air.
Such a parenchymatous tissue having large air spaces is called Aerenchyma.
These help in gaseous exchange and provide buoyancy to plant. Chlorenchyma :
When parenchyma is richly supplied with chloroplasts, it is called chlorenchyma.
They are found in leaf mesophyll, sepals, phylloclades, phyllodes, cladodes etc. It is photosynthetic in function and posses chlorophyll. Collenchyma :
It was discovered and coined by schleiden (1839).
The cells are living with intercellular space in between the cells or junctional places filled with cellulose and pectin.
Generally they are longer than parenchyma
Usually they are known as living mechanical tissue owing to their supportive functions.
It provides flexibility and strength to young plant organ.