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Permanent tissue is a type of plant tissue that does not have the ability to divide further. These tissues have completed their growth cycle and are composed of cells that do not undergo cell division.
- Permanent tissues are obtained by dividing and differentiating meristematic tissue.
- These tissues are found throughout the plant’s life.
- Permanent tissues consist of mature, differentiated cells that have low metabolic rates.
- These tissues are also known as differentiated tissues as they take permanent shape and size.
- The tissues help in providing support and protection in photosynthesis and the conduction of water, minerals, and nutrients.
- Permanent tissues contain large vacuoles, which are found inside these cells.
| Table of Content |
Key Terms: Permanent Tissues, Simple Permanent Tissues, Complex Permanent Tissues, Parenchyma, Chlorenchyma, Aerenchyma, Sclerenchyma, Xylem, Phloem
Types of Permanent Tissues
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Generally permanent tissues are divided into two types which are as follows:
Simple Permanent Tissues
Simple permanent tissue is a type of tissue that consists of only one cell. These tissues are also known as homogeneous tissues. They originate from the same source and have the same type of structure and functions.
- These tissues provide protection, storage, and mechanical support to plants.
- They are further classified into three categories, which are as follows:
Parenchyma
Parenchyma are basic packing tissues, i.e., tissues that form the base of plants. They are not specialized to perform any function. They have thin cell walls and large intercellular spaces.
The main functions of parenchyma are as follows:
- It provides support to the plants
- They help in storing food in plants so that they can use it whenever needed
- Parenchyma stores nutrients and water to supply to the plant as and when needed.
Parenchyma is divided into two types, which are as follows:
- Chlorenchyma: Chlorenchyma means parenchyma with chlorophyll and helps in the process of photosynthesis.
- Aerenchyma: Aerenchyma is parenchyma with air cavities in aquatic plants, which means that within the tissue, there will be big empty spaces containing air that help aquatic animals float.
Collenchyma
Collenchyma is the tissue responsible for providing flexibility in plants. This means that certain portions of plants can be moved or bent without breaking.
- Collenchyma is basically a supporting and strengthening tissue.
- It has elongated living cells and thick walls which are not regular.
- This tissue has fewer intercellular spaces.
- They are generally found in leaf stalks below the epidermis.
Sclerenchyma
Sclerenchyma is the tissue responsible for stiffness in plants, i.e., certain portions of plants are hard. They have long, narrow, and dead cells.
- Sclerenchyma also has thickened walls made of cellulose impregnated with lignin.
- Lignin is the chemical substance that makes the cell wall hard. It has no intercellular spaces.
- They are generally found in the hard covering of seeds and nuts, veins of the leaves, and stems.
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| Tracheids | Anatomy Of Flowering Plant | Transportation In Plant |
Complex Permanent Tissue
Complex permanent tissues are made up of multiple types of cells. They are used in transporting food, water, and minerals throughout the plant.
- All the cells of the tissues are coordinated to perform a common function.
- They are further classified into two categories, which are as follows:
Xylem
Xylem is found throughout the plant, and its main purpose is to transport water from the roots to the different parts of the plant. It mostly consists of dead cells. Xylem is basically made up of 4 different types of elements:
- Tracheid &vessels: They are tubular structures which will conduct water and minerals vertically
- Xylem Parenchyma: They help in the storage of food and transmit water sideways.
- Xylem Fibres: They are dead cells which only provide support.
Phloem
Phloem will distribute food from leaves to different parts of the plants. They are living cells except phloem fibres. It is made up of different elements:
- Sieve tubes: Sieve tubes forms a tube-like structure that helps in transportation. These sieve tube elements are joint end to end.
- Companion Cells: Companion cells help in regulating the metabolic activities of sieve tube elements. They are elongated and thin-walled. Its main function is to conduct food into different parts.
- Phloem parenchyma: It supports sieve tubes, which also store compounds like starch
- Phloem fibres: These are the dead cells which give mechanical support.
Special Tissues
Special Tissues are a modified category of permanent tissues used to carry out plant secretory functions. It is divided into two categories, which are as follows:
Laticiferous Tissues
Laticiferous Tissues originate from meristematic tissues and have latex. Their cells are elongated, thin-walled, and multinucleated. Euphorbiaceae, Apocynaceae, and Compositate are some types of Laticiferous tissues.
Glandular Tissues
Glandular Tissues consist of glands that help secrete oil, resins, tannin, and mucilage. They are located on the epidermis.
Things to Remember
- There are two types of tissues – meristematic tissue and permanent tissue.
- Permanent tissues are tissues that don’t have the ability to divide and are of a specific shape and size.
- There are two types of permanent tissue: simple permanent tissues and complex permanent tissues.
- Complex permanent tissue consists of the xylem and phloem.
- Extraxylary fibres are located at the cortex, pericycle, and phloem.
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Sample Questions
Ques: What are tissues? (2 marks)
Ans: Tissue are cellular organizational between cells and organ. The role of tissue is similar to that of cells and extracellular matrix from same origin that carries out specific functions. The word "tissue" is derived from the French word "tissue" which means “woven”. Organs are formed by functional grouping of multiple tissues.
Ques: What are the different types of tissues? Elaborate? (2 marks)
Ans: There are two types of tissues:
- Meristematic tissue- these are cells which keeps on actively dividing which leads to increase in the length and shape of the tissues. They have thin cell walls. They do not have intercellular spaces.
- Permanent tissue - tissues that are already present grown and they lose the ability to divide. These permanent tissues form specific structure and they start performing specific functions.
Ques: What are the different types of simple permanent tissues? Explain? (5 marks)
Ans: The different types of simple permanent tissues are as follows:
| PARENCHYMA | COLLENCHYMA | SCLERENCHYMA | |
|---|---|---|---|
| Cells | Living cells | Living cells | Dead cells |
| Intercelluar Spaces | Space is large | Space is less | No space |
| Cell Walls | Thin | Thickened at the corner irregularly | Lignin wall |
| Functions | Packing tissue, storage of food | Provides flexibility | Provides stiffness and support system to plants |
Ques:Explain the characteristics and functions of parenchyma? (3 marks)
Ans: Parenchyma are tissues that form the base of plants. They are not specialized to perform any function. They have thin cell walls and large intercellular spaces. Their main functions are:
- They provide support to the plants
- Parenchyma help in storing food so that they can use it whenever needed
Ques: What are the functions of xylem? (2 marks)
Ans: Xylem are specialized tissue of vascular plants that transports water and nutrients from the plant soil to stems and leaves and provides mechanical support and storage. It is the major conduction of water. They have elongated and aligned cells end to end. It helps to transport water and minerals vertically.
Ques: What are the functions of Phloem? (3 marks)
Ans: Phloem is another vascular tissue found in plants. It locates food matter from leaves to different parts of the plants. It contains chlorophyll. It also plays an important role in photosynthesis. Its main role is to transport carbohydrates from sources to sinks through sieve elements. It also plays an important role in storage of water.
Ques: Where permanent tissues are found? (3 marks)
Ans: Permanent tissues are found in all mature plants. They carry out different functions with the plant body. Simple permanent tissues are found below the epidermis of the plant, spread around in layers of cells. Parenchyma is found in the cortex of stem and roots. Collenchyma is found in the leaf stalk and below the epidermis. Sclerenchyma is found in stems, around the vascular bundle, around the hard covering of seeds and nuts, and in veins of leaves.
Ques: What are the functions of collenchyma? (3 marks)
Ans: Collenchyma tissues are generally composed by elongated living cells of thick walls. It provides support, structure, mechanical strength and flexibility which allow easy bending without breaking. It has less intercellular spaces. They are generally found in leaf stalks below epidermis. Collenchyma tissues takes part in photosynthesis thus provides synthesises carbohydrates.
Ques: What is the difference between xylem and phloem? (4 marks)
Ans: The difference between xylem and phloem are as follows:
| Xylem | Phloem |
|---|---|
| Xylem has unidirectional flow | Phloem has bidirectional flow |
| It transports water & minerals from roots to aerial plant parts | It helps in transporting food & nutrients from leaves to different plant parts |
| Dead tissues at maturity | They are living tissues |
| Occurs at centre of vascular bundle | They occur on the outer side of vascular bundle |
Ques: What are the functions of permanent tissue? (3 marks)
Ans: The functions of permanent tissues are as follows:
- Support: Permanent tissue provide the plant structural sturdiness.
- Storage: It helps in holding onto nutrients, such as water and carbohydrates.
- Transport: It will encourage the flow of nutrients, minerals, and water.
- Specialized Functions: It will fulfill certain duties like as defense and secretion.
Ques: What are different types of Collenchyma? (3 marks)
Ans: The different types of collenchyma are as follows:
- Tangential Collenchyma: This type of collenchyma is characterized by rows of lined cells that are thicker at the tangential portion of the cell wall.
- Lacunar Collenchyma: The cells in this collenchyma include space.
- Angular Collenchyma: This type of collenchyma has thicker intercellular contact sites.
- Annular Collenchyma: This type of collenchyma has consistently thicker cell walls.
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