What is Parenchyma?
Parenchyma is a plant, tissue typically composed of living cells that are thin-walled, unspecialized in structure, and therefore adaptable, with differentiation, to various functions. The cells are found in many places throughout plant bodies and, given that they are alive, are actively involved in photosynthesis, secretion food storage, and other activities of plant life.
Parenchyma cells can serve many functions. Their role is largely based on their location in the plant; that can determine whether they will serve in storage, photosynthesis, or damage repair.
Parenchyma cells have large central vacuoles, which are large, membrane-enclosed organelles found in many plant cells. These vacuoles are able to be used by plant cells to store materials and to maintain optimal pressure within the cell of the plant.
What is Collenchyma?
Collenchyma cells are elongated cells with irregularly thick cell walls that provide support and structure. Their thick cell walls are composed of the compounds cellulose and pectin. These cells are often found under the epidermis, or the outer layer of cells in young stems and in leaf veins.
Collenchyma cells provide structural support, protecting the plant by serving as an inner framework, much like bones do for humans and other animals. Plants are exposed to numerous structural challenges and without these cells, most plants would be too fragile to withstand the damage caused by heavy rains, high winds, and other stresses.
The thickened walls of the collenchyma cells enable them to provide additional support to the areas where they are found. Most notably, collenchyma cells serve growing parts of the plant, such as shoots and leaves, both by providing support and by filling in vacant spaces that will be used for later growth.
What is Sclerenchyma?
Sclerenchyma cells are specialized plant cells that exist to provide strength and support. They are present in all kinds of plants including grasses, trees, and flowering plants.Sclerenchyma cells are strong, thick cells that provide most of the support in a plant. They are known to have extremely thick cell walls and do not participate in many of the other activities of the developing plant, such as photosynthesis, because their focus is strictly on support and structure.
Mature sclerenchyma cells are usually dead cells that have heavily thickened secondary walls containing lignin. The cells are rigid and nonstretchable and are usually found in nongrowing regions of plant bodies, such as the bark or mature stems. Once they’re dead, they simply maintain the structure of the plant and do not require further maintenance, freeing the plant to concentrate on other areas while having the support and strength it needs.
Parenchyma vs Collenchyma vs Sclerenchyma
| Elements of comparison | Parenchyma | Collenchyma | Sclerenchyma |
| What are they | They are thin-walled cells that make up the inside of non-woody plant structures including stems, roots and leaves. | They are plant tissues that consist of living elongated cells with unevenly thickened walls and acts as support especially in areas of primary growth. | Is a supportive or protective tissue in higher plants (vascular plants) composed of cells with walls thickened and often lignified. |
| Cell wall Thickness | Made up of cells having very thin cell wall that is uniformly thickened. | Made up of unevenly thickened cell wall. | Made up of a thick and rigid cell wall. |
| Presence | Cells are found in every soft part of the plant like leaves, fruits, bark, flowers, pulp and pith of the stems. | Cells are found in petiole, leaves and young stems, appearing as a continuous ring beneath the epidermis. | Cells are found in the mature parts of the plant like herbaceous perennials and woody plants. |
| Cell Shape | Usually isodiametric in shape, however they can still have other various shapes. | Cells are usually polygonal in shape. | Cells are tubular in shape. |
| Cells | They are unspecialized cells. | They are specialized cells. | They are specialized cells. |
| Cell wall components | Cell wall is made up of cellulose. | Cell wall is made up of pectin and hemicelluloses. | Cell wall is made up of waterproofing lignin. |
| Intercellular Spaces | Cells are loosely packed. | Cells have little space between cells. | Cells have no intercellular spaces present between them, cells are tightly packed. |
| Cell Constituents | Consists of living cells at maturity. | Consists of living cells at maturity. | Consists of dead cells at maturity and thus why protoplast is absent. |
| Composition | Found abundantly in plant tissues. | Collenchymacells make up the epidermal layers. | Found in plenty on the outer woody stem portion of large trees. |
| Cells Origin | Cells originate from protoderm and ground meristem. | Cells originate from pro-cambium like cells in the ground meristem. | Cells originate from protoderm pro-cambium and ground meristem. |
| Function | Plays a major role in gas exchange, storage of food and photosynthesis. | Providing mechanical support to the plant and elasticity to the plant. | Provide mechanical support to the plant. It also supports transportation of water and nutrients to the plants. |
| Pit Fields | Cells have primary pit fields on the cell wall. | Cells have no pit fields on the cell wall. | Cells have simple and bordered pit fields. |
| Cell Wall | The cell walls are primarily in nature without sculpturing. | The cell walls are primarily in nature with no sculpturing. | Cell walls are formed secondarily with various sculpturing like annular, spiral and reticulate etc. |