The cells of the parenchyma are the type of living plant cells known for their healing and repair mechanisms and food storage. The collenchyma cells are known to provide mechanical support to plants, protecting the delicate inner part of the plant’s plant. Sclerenchyma cells are mature dead cells and are found in the woody or hard stem part of the plant.
Just as humans, which have bones to support their body structure, plants also have certain specialised tissues that help them by supporting their structure, protecting internal parts, giving them strength, etc. These three tissues (Parenchyma, Collenchyma and Sclerenchyma) are considered to be the fundamental tissues of plants and are known to provide mechanical strength to the plant from its growth stage throughout its life.
In addition to the points mentioned above, plant tissues also help in the division of new cells and in the growth of new plants. It also helps in various metabolic activities. They also help the tissues of leaves, stems and branches to bend and protect them from damage.
Tissues are formed from a group of cells that perform a specialised function. Plants are also multicellular organisms, containing numerous cells, each of which is assigned to a specific activity. Generally, there are two types of plant tissues, these are Meristematic and Permanent tissues. Permanent tissues are again divided into simple permanent tissues and complex permanent tissues.
In this article, we will focus on the three types of simple permanent tissues, which are parenchyma, collenchyma and sclerenchyma tissues. We will also discuss the fundamental point on which they differ.
Comparative table
| Basis of comparison | Parenchyma | Collenchyma | Sclerenchyma |
|---|---|---|---|
| Meaning | The living plant cells originate in the meristem ground meristem and protoderm. These types of cells are found most abundantly in the tissue vegetable. | The type of living plant cells that originate in the pro-cambium. The epidermal layers of the plant consist of collenchyma cells. | The hard, outer part of the stem is formed by sclerenchyma cells. These are the dead plant cells that originate from the ground meristem and the procambium protoderm. |
| It is found in | This type of cell is present in all soft parts of the plant. | These cells are found in specific parts of the plant such as leaves, stems and petioles. | Found in mature parts of plants or trees. |
| Cell type | Living, unspecialised cells. | Specialised cells and living cells. | Specialised, mature and dead cells. |
| Cell form | There are various cell shapes, but they are generally isodiametric. | There are elongated cells. | Sclereids, elongated and fibre-shaped. |
| Cell wall | Presence of thin cell wall. | Uneven cell wall. | Presence of hard, thick cell wall. |
| The cell wall consists of cellulose. | The cell wall consists of pectin and hemicellulose. | The cell wall consists of lignin. | |
| Intercellular space between cells. | Present. | There is less space between cells. | Absent and therefore the cells are very tightly packed. |
| Function | Parenchyma cells assist in food storage, gas exchange and the photosynthesis. | The collenchyma cells provide mechanical support and elasticity to the plant. | Sclerenchyma cells provide mechanical support to the plant. They also support the transport of water and nutrients to the plants. |
Definition of parenchyma
Parenchyma is the simplest tissue made up of living cells and forming the thin layer called the primary cell wall of the plant. Parenchyma comes from the Greek word “parenchyma”, meaning “something poured alongside”. In plants, parenchyma cells are widely distributed throughout and occur as a continuous mass from stems to roots, leaves and fruits.
Parenchyma cells are responsible for generating many other specialised cells and tissues. Structurally they are isodiametrically shaped as they have thin cell walls, so they face force and pressure around the cell walls and in this condition, the cell increases its volume capacity, to equalise the pressure in all cells.
Cell walls are composed mainly of hemicellulose and cellulose. Parenchyma cells abound in organelles such as ribosomes, Golgi bodies, endoplasmic reticulum, chloroplast and other contents such as pigments, starch, fats and proteins. These contents provide nutrients to the embryo at germination.
Due to its cellular structure, parenchyma performs multiple functions in different parts of plants. Some of the main functions of parenchyma cells are storage, transport, gas exchange, protection, photosynthesis, repair of damaged tissues and generation of other specialised cells. Thus, parenchyma cells play a vital role in the overall development of the plant throughout its life.
Definition of collenchyma
It is known that the cells of the collenchyma provide structural support to the cell. They are also living cells and have thick cell walls. The cell walls of collenchyma cells are composed of pectin, hemicellulose and cellulose. The cells have a nucleus prominent with other organelles.
The collenchyma also stores food, prevents leaf tearing and also performs the function of photosynthesis. The collenchyma cells drive the plant organs to elongate and grow.
These cells are absent in the monocots and even in the roots of all plants, although they are present in the leaves of dicotyledons on top of the petiolethe veins of the leaves and the midrib. There are three different types of collenchyma cells, which are angular, lacunar and lamellar.
Definition of sclerenchyma
As mentioned above, sclerenchyma is called dead plant tissue because it is part of the hardwood. The secondary walls of mature sclerenchyma cells are densely packed and contain lignin and hemicellulose. These cells are hard, non-growing and non-stretching and are present in mature stems or bark.
Sclerenchyma are found in many different sizes and shapes, but sclereids and fibres are the main types. Sclereids are found in tissues such as the xylemthe phloemthe pith, pith, cortex and peridermis. This cell also contributes to the hard covering of nuts, fruits and other seeds.
Fibres support plants, as they are elongated cells present en masse in every part of the plant. Some types of fibres, such as leaves and seed hairs, are also economically important because they are used as woven and textile materials.
Key differences between parenchyma, collenchyma and sclerenchyma.
The following points will differentiate the three types of terrestrial tissues present in plants, which are parenchyma, collenchyma and sclerenchyma:
- Parenchyma is one of the cell types living plant cells that originate from the ground meristem and protoderm. These types of cells are found most abundantly in plant tissue. Another type of living plant cells that originate from the pro-cambium are those known as collenchyma cells. The epidermal layers of the plant are formed by these cells. Thirdly, the hard, outer part of the stem is formed by sclerenchyma cells. These are the dead plant cells that originate from the ground meristem and the procambium protoderm.
- Parenchyma cells are are found in all soft parts of the plant, but collenchyma cells are found in specific parts of the plant such as leaves, stems and petioles, while sclerenchyma cells are found in mature parts of plants or trees.
- There is different types of shapes of all cells, but generally, parenchyma cells are isodiametric, while collenchyma are elongated and sclerenchyma are sclereid, fibre-shaped respectively.
- The parenchyma has a cell wall The cell walls of collenchyma cells have a thin cell wall and are made of cellulose. Whereas the collenchyma cells have an uneven cell wall consisting of pectin and hemicellulose. There is a hard, thick cell wall present in sclerenchyma cells, which is formed by lignin.
- The intercellular space between cells is present in parenchyma cells, whereas in collenchyma cells there is less space between cells and in sclerenchyma cells, intercellular space is absent because the cells are tightly packed.
- The function of parenchyma cells is in food storage, gas exchange and photosynthesis, while collenchyma cells provide mechanical support and elasticity to the plant, sclerenchyma cells provide mechanical support to the plant. It also supports the transport of water and nutrients to plants.
Conclusion
We are all aware of the importance of tissues in both plants and animals, in this article we studied plant tissues and their specialised functions. Although the anatomy plant also has different categories of tissues such as the vascular tissueThe epidermis and the fundamental tissues, above we study only the fundamental tissues and how they vary from each other.