Parenchyma Cells

Parenchyma is one of the simple permanent tissues that help in creating a major portion of fundamental or ground tissues in plants. There are mainly three types of simple permanent tissues found in plants – Parenchyma, Collenchyma, and Sclerenchyma.

However, among these three types of ground cells, only parenchyma cells consist of thin-walled, living, simple, and structure-wise unspecialised cells. Thus, these cells are adaptable for several functions.

Notably, these ground tissues are neither embedded nor vascular. Moreover, parenchyma tissue is alive, and hence it can be involved in secretion, food storage, photosynthesis, and various other life processes of plants.

Characteristics of Parenchyma

There are some fundamental characteristics seen in parenchyma cells. Those are-

  • After reaching maturity, these permanent living cells can divide. With this characteristic, these tissues can help in the healing of wounds and regeneration.

  • Parenchyma is the foundation of most plant cells. The reproductive cells of plants like gametes, spores, etc. are parenchymatous.

  • Plant zygotes are also made of single parenchyma. Thus, a parenchymatous zygote can grow into an entire plant through cell division. These cells are known as “totipotent” cells.

  • This cell can appear as continuous masses like the cortex & pith of roots and stems, the endosperm of seed, mesophyll of the leaf, the flesh of juicy fruits, etc. This type of tissue is called homogeneous parenchyma tissue.

  • Parenchyma can create heterogeneous complex tissues by associating with different kinds of cells. The parenchyma present in phloem or xylem is an example of heterogeneous parenchyma.

  • Essential life process activities like storage, assimilation, photosynthesis, excretion, respiration, transportation of water throughout the body, etc. require these cells.

Structure of Parenchyma

Parenchyma cells are living cells. A vital part for respective organisms, its basic structural characteristics are noted below.

  • This ground cell consists of prominent protoplasts and nuclei.

  • Mostly, parenchymas are polyhedral or isodiametric in shape. However, these cells can be round, oval, elongated, or polygonal as well. 

  • The intercellular space of parenchyma is small, and the cells might also be tightly packed.

  • They have thin cell walls which are composed of hemicelluloses and cellulose.

  • In a parenchyma tissue, plasmodesmata joins all the cells.

  • These cells have multiple small vacuoles. In older parenchyma, these small vacuoles fuse and form a large central vacuole. This large vacuole can accumulate tannins or anthocyanin.

  • Vacuoles in parenchyma have abundant water, and they work as water reservoirs of plants.

  • Storage parenchyma can have thick cell walls of xyloglucan like the endosperm of a date palm. During the germination of seeds, the sugar is utilised and the walls are reduced to thin layers.

  • Chromoplast is present in the parenchyma of fruits and flowers.

  • Sometimes, parenchyma also has a thick lignified cell wall similar to sclerenchyma.

  • The mechanical strength of parenchyma is derived from the cell’s hydraulic property.

  • Parenchyma contains chloroplast that specifically performs photosynthesis.

  • Some parenchyma cells contain dense protoplasm that is highly composed of endoplasmic reticulum, golgi bodies, and ribosomes. These cells help in performing a secretory function.


Depending on the location, structure, and functions, parenchyma can be divided into the following categories-

Types of Parenchyma

Parenchyma type

Description

Chlorenchyma

Parenchyma with chloroplast that helps in performing photosynthesis is called chlorenchyma.

Transfer cell

These parenchyma cells transport the solutes over a shorter distance.

Vascular parenchyma

This parenchyma is composed of vascular tissues. They are of two types- phloem parenchyma and xylem parenchyma. Phloem parenchyma consists of cylindrical, elongated, and tapering cells with dense cytoplasm.

Xylem parenchyma has thin walls of cellulose.

Storage parenchyma

This parenchyma acts as the reservoir of water and food of the cell. These cells also contain starch, protein, etc.

Prosenchyma

This thick-walled parenchyma provides strength and rigidity to the cell of the plant.

Aerenchyma

Contrary to another parenchyma, this cell has a large intercellular space. They are mostly seen in the aquatic plants.

Epidermis parenchyma

Some gymnosperms have these cells in their epidermis.

Conjunctive parenchyma

In the root system of plants, this parenchyma is found.


Functions of Parenchyma

Parenchyma helps to perform different biological functions.

  • Storage

The intercellular space between parenchyma cells works as the storage of water, starch, fats, etc.

  • Photosynthesis

Chlorenchyma carries chloroplast that is present in all green parts of a plant and performs photosynthesis.

  • Transport

Parenchyma tissue transports water, nutrients, and other important chemicals throughout the plant body.

  • Protection

The spiny projections in the parenchymatous cells of gymnosperms protect them from predator attacks.

  • Gas exchange

Aerenchyma helps in the exchange of gasses.

  • Totipotent

Parenchyma can transform into other kinds of cells in case they predecease. 

  • Regeneration and healing

The ability of cell division of parenchyma helps in healing body wounds with their regeneration.

  • Buoyancy

Aerenchyma consists of air sacs that help the aquatic plants to float.

The above discussion provides a comprehensive understanding of parenchyma cells which includes its characteristics, types and functions. You should note them in detail since it is one of the vital topics in your curricula.

Prepare Well, it is Yours for the Taking!

While preparing for NEET, you must remember that a healthy mind also requires a healthy body. So, you must take care of your health to give your best attempt in this examination. You should try out some physical exercise like yoga, walking in the fresh air to keep your mind and health fit.

As long as you are fit, you will also be able to maintain your study schedule properly and prepare every important topic like parenchyma cells and others for your NEET examination. You should also make it a point to regularly practice questions on the parenchyma tissue and its related topics from previous years as well.

Stay fit and healthy. Best of luck for the NEET examination.

FAQ (Frequently Asked Questions)

1. What is the main function of parenchyma cells?

Ans. Parenchyma is living cells at maturity. The primary functions of these cells are in photosynthesis, storage, and that of acting as vascular and ground tissue.

2. Where is parenchyma found?

Ans. Mostly, parenchyma is found in the mesophyll of leaves, phloem and xylem, medullary rays, pith, cortex of roots, etc.

3. Where do you find parenchyma cells in humans?

Ans. Parenchyma signifies the cell that can help in the biological functions of organs. Thus, nervous tissues of the brain, lung cells that help in respiration, liver cells that purify the blood, etc. are parenchyma cells in the human body.