Parenchyma cells form the ground tissue in plants and perform many important functions. They can store starches, fats, oils, and water. Parenchyma cells also transport nutrients throughout the plant and perform photosynthesis using chloroplasts. Additionally, parenchyma cells play roles in gas exchange, protection, buoyancy, healing, and regeneration. Parenchyma cells occur in continuous masses and can be polyhedral, stellate, elongated, or lobed in shape. The mesophyll tissue in leaves contains palisade parenchyma above spongy parenchyma.

1. TISSUE, TISSUE TYPES AND
TISSUE SYSTEM

4. • They are living permanent tissues that have the ability to divide at maturity and help in
the regeneration and healing of wounds
• Parenchyma cells are the foundation of a plant as reproductive cells (spores, gametes)
are parenchymatous in nature
• Single parenchyma cell of a zygote has an ability to develop into an entire plant. These
cells are called “totipotent” cells
• Parenchyma cells occur in the form of continuous masses as homogeneous parenchyma
tissues e.g. in pith and cortex of stems and roots, mesophyll of leaves, the flesh of
succulent fruits and in the endosperm of seeds
• Parenchyma cells may be associated with other types of cells to form heterogeneous
complex tissues such as parenchyma of xylem and phloem
• Parenchyma cells are essential for activities like photosynthesis, storage, secretion,
assimilation, respiration, excretion and radial transport of water and solute
• Structure of Parenchyma Cells

7. Functions of Parenchyma cells
Parenchyma cells form the ground tissue of plants. Parenchyma tissues perform
various important functions:
Storage: Parenchyma cells have large intercellular space which is ideal for storage
High amount of starch is present in the tubers of potato and cassava
These can store water, fats, oil droplets.
Store water and act as a water reservoir
Transport: Parenchyma cells transport nutrients and other chemicals
Transfer cells have outgrowth for increasing absorption surface
The xylem parenchyma helps in radial transportation of water and minerals
Some cells transport light from the surface to underground cells
Photosynthesis: Chlorenchyma present in the mesophyll and the other green parts of
the plant, have chloroplasts and perform photosynthesis
Gas Exchange: Aerenchyma cells help in the gas exchange
Protection: In gymnosperms, the parenchymatous cell have spiny projections that help
in the protection from predators
Buoyancy: Aerenchyma present in aquatic plants have air sacs that help in floating
Healing and regeneration: Parenchyma cells which retain their ability to divide even
on maturity help in regeneration and wound healing. Tyloses present in the xylem
parenchyma help in preventing damage to vascular tissues in the condition of drought.

8. SHAPES OF PARENCHYMA CELLS:
• Polyhedral: These cells are mostly polyhedral in shape.
• Stellate: These parenchyma are kund in the stems of plants. They have well
developed air spaces between them.
• Elongated: Elongated parenchymas are found in the palisade tissue of leaf.
• Lobed: Lobed parenchymas are found in spongy and palisade mesophyll
tissues of some plants.
• Leaf consist of mesophyll cells which are of two types. Palisade mesophyll
(tightly packed) and spongy (loosely arranged) mesophyll (parenchymatous
cells)
• Xanthorrhaceae