Parenchyma is a simple permanent tissue that is made up of thin-walled living similar oval, rounded or polygonal isodiametric cells with or without intercellular spaces. It is composed of living cells that are different in structure and perform their functions continuously. These cells are located in different parts of plants and actively participate in photosynthesis, secretion, food storage, and other fundamental activities of plants. Parenchyma is mainly found in the non-woody or soft areas of steams, leaves, roots, flowers, fruits, etc. It is one of the main Tissue in plants with sclerenchyma and collenchyma.
Parenchyma is composed of chloroplast-laden mesophyll of leaves and cortex with the pith of stems and roots. It is also contained in the xylem and phloem of the plant. This tissue can be found in compact form or have large intercellular space. Parenchyma is classified into 9 types.
Types of Parenchyma Tissue
1. Epidermis
It is the outermost single layer of aerial parts of plants (stem and leaf). It is made up of thin-walled living barrel-shaped compactly arranged parenchymatous cells without intercellular spaces. It is covered externally by the cuticle. Epidermal hair and stomata may be present. Epidermis reduces the rate of transmission by cuticle, exchanges of gases through stomata, protects inner tissue, and also helps in heat insulation by epidermal hairs.
2. Epiblema
Epiblema is single-layered radially elongated parenchymatous cells of the root without intercellular spaces. Some cells of epiblema elongate to form unicellular tubular outgrowth called call Rupa root hairs. Due to the presence of root hairs, it is also called the piliferous layer. This layer helps to absorb water and mineral salts from the soil. Root hairs increase surface area for absorption of sap.
3. Simple Parenchyma
It is thin-walled living isodiametric oval or rounded cells with intercellular spaces or polygonal cells without intercellular spaces. It is found in soft parts of root, stem, leaf, flower, etc. It helps in the storage of food and also provides turgidity to the software parts of the plant.
4. Chlorenchyma
Parenchymatous tissue having chloroplasts that help in photosynthesis is called chlorenchyma. it is found in the young green stems, green fruits, and leaves. Chlorenchyma present in leaves is called mesophyll tissue. It is differentiated into palisade parenchyma and spongy parenchyma. Cells of palisade parenchyma are columnar in shape with intercellular spaces and have a single row of chloroplasts but cells or spongy parenchyma are oval, rounded, or irregular in shape with air cavities and have few scattered chloroplasts.
5. Aerenchyma
A special parenchymatous tissue with air capacities is known as parenchyma. It is found in aquatic plants and some land plants (xerophytes ). It is made up of thin-walled living oval, rounded or irregular parenchyma with very large air cavities. These air cavities store gases and make aquatic plants light and buoyant. In xerophytes and succulents, it helps in the storage of water.
6. Prosenchyma
It is a slightly thick-walled living fiber-like elongated parenchyma. It is found in pericycle and conjunctive tissues. It helps in mechanical support and storage of food.
7. Idioblast
It is made of large-sized parenchyma cells which possesses cell inclusions or ingredients like tannins, oils, crystal, etc. It helps in the storage of excretory products.
8. Phloem Parenchyma
It is thin-walled elongated polygonal parenchymatous cells without intercellular spaces present in the phloem. It helps in the storage and slow lateral conduction of food.
9. Xylem Parenchyma
It is thin-walled elongated polygonal parenchymatous cells without intercellular spaces present in the xylem. It helps in storage and slow lateral conduction of water.
The function of Parenchyma
- Parenchyma mainly helps in the storage of food.
- It provides turgidity to softer parts of plants.
- Epidermis mainly helps in the protection of inner tissue.
- Chlorenchyma helps in photosynthesis.
- Arerenchyma provides buoyancy and storage of metabolic gases.
- Phloem and xylem parenchyma helps in the slow lateral conduction of materials.
- Epiblema helps in the absorption of sap.
- Idioblast helps in the storage of excretory products.
- Prosenchyma helps in mechanical support.
- Cells of parenchyma may undergo dedifferentiation and form cork cambium of phellogen that helps in secondary growth.
Hence, these are the types and functions of Parenchyma Tissue. If you have any confusions and queries related to this topic then please comment down.
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