Plant tissue is a complex network of cells that work together to achieve the various functions of a plant. Plant tissue is comprised of four distinct types: meristematic, permanent, and ground. Each type of plant tissue is vital for a plant to survive and thrive in its environment.
Types of Plant Tissue
Types of Plant tissue can be understood by this classified chart:
1. Permanent Tissue
Permanent tissue is composed of cells that are usually specialized for a particular function within the plant. These cells tend to be more rigid and less flexible than meristematic tissue. The cells in permanent tissue are usually permanently dead and can no longer divide. 
Examples of permanent tissue are parenchyma, sclerenchyma, collenchyma, and xylem and phloem.
Parenchyma cells are usually responsible for storage of photosynthetic products, water, and minerals. Sclerenchyma cells provide support and protection to the plant. They are often found in the outer layers of plant stems, leaves, and roots. Collenchyma cells are also supportive, but they are more flexible than sclerenchyma cells. The xylem and phloem are responsible for transporting water and other substances throughout the plant.
There are two main types of Permanent tissue as mentioned below:
1. Simple Permanent Tissue 2. Complex Permanent Tissue
1. Simple Permanent Tissue of plants
Simple permanent tissue is a type of tissue found in plants that is made up of three types of cells – parenchyma, collenchyma, and sclerenchyma. These cells work together to provide support, store food, and help transport water and minerals throughout the plant.
Simple permanent tissue plays an important role in the overall structure and function of a plant.
There are 3 subcategories of Simple Permanent Tissue:
a) Parenchyma
Parenchyma is a type of tissue composed of living cells in the form of thin-walled cells that contain an abundance of cytoplasm and a nucleus.
This type of tissue is found in most organs and is responsible for the metabolic activities associated with the organ. It is also the main type of tissue in plants and is made up of thin-walled cells that are filled with chloroplasts, which are responsible for photosynthesis.
Parenchyma cells provide structural support and help to regulate the temperature of the organ they are found in.
b) Collenchyma
Collenchyma is a type of plant tissue that provides structural support for the plant and where necessary, aids in the transport of water and minerals throughout the plant. It is composed of living cells, typically with thicker walls on the sides of the cells and thinner walls on the ends.
Collenchyma cells are usually elongated and can be found in regions of the plant where support is needed such as petioles, leaf veins, and stems. It is able to stretch and bend when the plant grows or is exposed to wind, making it an important part of the plant’s support system.
c) Sclerenchyma
Sclerenchyma is a type of plant cell that contains lignin, a substance that makes them strong and rigid. These cells are found in the stems and veins of plants, providing support and structure.
They are often found in the outer parts of the plant and form the bark, wood, and other protective layers.
Sclerenchyma cells are also responsible for transporting water and other substances throughout the plant. They are vital for the survival of the plant and are the cells that give plants their structure and strength.
2. Complex Permanent Tissue of plants
Complex permanent tissue of plants are divided into two major types: Xylem and Phloem.
A) Xylem
Xylem is composed of living cells and is responsible for transporting water and minerals from the roots to the rest of the plant and is also responsible for providing structural support. It is made up of several different cell types, including tracheids, vessel elements, and xylem parenchyma cells.
Xylem cells have thick walls and are arranged in a continuous network throughout the plant, allowing for efficient transport of water and nutrients.
These are 4 main parts of xylem:
a) Tracheids
are long, narrow cells that are characteristic of the secondary xylem tissue. They have thick walls with lignin and allow water and mineral ions to move through them to the rest of the plant.
Tracheids are usually arranged in chains, with each cell connected to the next via pits in their cell walls. These pits, known as pit membranes, control the flow of water and nutrients from one tracheid to the next.
b) Vessels
Xylem vessels are long tubes made up of dead cells that form a continuous pathway from the roots to the leaves. They are arranged in a series that acts as a pipeline to transport water and minerals from the roots to the leaves.
Xylem vessels also help to provide structural support by connecting the cells of the plant. Additionally, they are important in the process of transpiration, where water evaporates from the leaves to the atmosphere.
c) Xylem Parenchyma
Xylem Parenchyma cells are mainly involved in the storage and transport of water and minerals. They have secondary cell walls and are located in the lateral walls of the xylem.
They can also be found in the phloem, where they are involved in the transport of organic substances. They are also responsible for the storage of food.
d) Xylem Fibres
Xylem fibers are a type of plant cell that are essential for the functioning of the plant as they provide nutrients, water, and structural support. They are made up of lignified secondary cell walls and are found in all parts of the plant, including the stems, leaves, and roots.
They are composed of a variety of cell types, including tracheids, vessels, and parenchyma cells, and are responsible for transporting water and minerals from the roots to the leaves and other parts of the plant.
B) Phloem
Phloem is composed of sieve tubes and companion cells. Sieve tubes are specialized cells that transport sugars and other organic molecules throughout the plant. They are connected end-to-end, forming a continuous tube that runs from the roots to the leaves.
Companion cells help regulate and support the sieve tubes. Together, these cells form a complex network that transports the products of photosynthesis throughout the entire plant.
These are 4 main parts of Phloem:
a) Sieve Tube of Phloem
The sieve tube of phloem is made up of sieve tube elements, which are connected to each other through sieve plates. The sieve tube elements are long, slender, and elongated cells, which lack a nucleus, ribosomes and other organelles.
They are connected end-to-end with the help of sieve plates that contain perforated sieve areas. These perforations allow the transfer of proteins, from one cell to another, via the sieve plates.
Additionally, the sieve plates also allow the passage of fluids, such as water and other organic molecules, from one cell to another. The sieve tube elements are also connected together with the help of companion cells, which are found in between the sieve tube elements. The companion cells help to regulate the flow of materials in and out of the sieve tube elements.
b) Companian Cells of Phloem
Companian cells of phloem are also known as “companion cells”. They form a specialized type of living cell that is typically found in association with sieve-tube elements in phloem tissue. Companion cells are thought to be involved in the loading and unloading of metabolites into and out of the sieve-tube elements.
They are also believed to be responsible for the regulation of ionic, metabolic, and regulatory functions in the phloem. This includes the regulation of solute and water transport, as well as the maintenance of pH balance. Companion cells also play a role in the regulation of the permeability of the sieve-tube elements. Finally, they may also be involved in the control of the metabolic activity of the sieve-tube elements.
c) Phloem Parenchyma
Phloem Parenchyma is a type of plant tissue that helps in the conduction of food and other organic materials throughout the plant. It is a living cell found in the phloem, the vascular tissue of plants that transports sap and other substances from the leaves to other parts of the plant. Phloem parenchyma cells are thin-walled and have a large central vacuole.
They are responsible for synthesizing, storing, and transporting substances throughout the plant. They also play an important role in aiding in the mechanical support of the plant.
d) Phloem Fibres
Phloem fibres are cells found in the phloem tissue of plants and form part of the vascular bundle. They are composed of a lignin-rich cell wall and are usually narrow, elongated cells. The main role of phloem fibres is to provide structural support to the phloem tissue, enabling it to transport nutrients and other substances throughout the plant.
Phloem fibres are also important in the process of secondary thickening, which occurs when plants experience mechanical stress or pressure. This process is necessary for plants to maintain their structural integrity and prevent the damage that would occur from the stress.
2. Meristematic Tissue
Meristematic tissue is a type of plant tissue that is undifferentiated and capable of cell division. It is often found in areas of the plant where growth is taking place. Meristematic tissue is responsible for the growth of plant organs such as stems, roots, and leaves.
Meristematic tissue can also be found in the cambium layer of the plant, which is responsible for the growth of secondary tissues. There are three types of meristematic tissue: apical, intercalary and lateral.
a) Apical Meristem
The apical meristem is the main source of new cells for the plant body and is found in the root and shoot tips of the plant. It is responsible for the growth at these sites.
It contains undifferentiated cells that divide rapidly and give rise to daughter cells that can differentiate into any of the three tissue types – ground tissue, vascular tissue, and dermal tissue.
This process of differentiation is termed as differentiation of the meristematic cells. The apical meristem is a small region of actively dividing cells at the tips of the shoot and root. It is responsible for the continuous growth of the plant in the longitudinal direction.
The cells of the apical meristem are organized into three distinct layers, each with different functions.
The outermost layer is the tunica, which produces the primary meristematic cells.
The middle layer is the corpus, which produces the secondary meristems and the innermost layer is the columella, which produces the tertiary meristems.
The apical meristem is essential for the growth and development of the plant as it maintains the plant body’s shape and size.
Ground tissue
Ground tissue is the most abundant and widely distributed type of tissue in a plant. It consists of three cell types: parenchyma, collenchyma, and sclerenchyma. This tissue type is responsible for photosynthesis, food storage, and cell expansion.
Vascular tissue
Vascular tissue is a complex conducting tissue present in plants, which is essential for transporting water and nutrients throughout the plant. It is composed of xylem and phloem cells, which are responsible for transporting water, minerals, and sugar, respectively.
Dermal tissue
Dermal tissue is a single-layered protective tissue that covers the outer surface of the plant body. It is composed of epidermal cells, which are responsible for absorbing water and minerals, protection from water loss, and also for providing a barrier to pathogens.
b) Intercalary Meristem
Intercalary meristem is a type of meristem found in the stems and leaves of many monocots. It is a zone of actively dividing cells located at the base of the internodes, between the leaf and the stem.
It is responsible for the elongation of the stem, and for the production of growth rings in monocots, including grasses and other plants.
Intercalary meristem also produces secondary growth, which increases the girth of the stem. This growth is important to the strength of the stem and its ability to resist breakage.
c) Lateral Meristem
The lateral meristem is a type of plant tissue responsible for the lateral growth of plants.
This tissue is made up of two main types of cells, the vascular cambium and the cork cambium.
The vascular cambium
The vascular cambium is responsible for the growth of secondary xylem and phloem in plants.
Cork cambium
Cork cambium is responsible for the production of protective layers of cork cells on the outer surface of the plant.
The lateral meristem is generally located just below the epidermis of the plant, and is responsible for the production of secondary growth, which increases the width of the plant and helps to support it.
Difference between Xylem and Phloem
1. Xylem and Phloem are both important components of a plant’s vascular system and are responsible for transporting fluids and nutrients throughout the plant.
2. Xylem is the tissue that transports water and minerals up from the roots through the stem to the leaves. It is composed of hollow tubes that are strengthened by lignin.
3. On the other hand, Phloem is the tissue that transports sugars and other organic nutrients produced during photosynthesis from the leaves to other parts of the plant. It is composed of living cells that contain sieve tubes and companion cells.
4. Xylem and Phloem are both vitally important for the health and functioning of a plant, but their structures and functions are distinct.
5. Xylem contains vessels that provide support for the plant, while Phloem does not.
Protective Tissues of Plants
Protective tissues of plants are important for the protection of plants from environmental stresses and external threats that can otherwise lead to the death of the plant.
Examples of protective tissues are the cuticle and the epidermis.
Cuticle
The cuticle is a wax-like layer that covers the outer surface of the plant and helps to protect it from water loss, desiccation, and environmental threats.
Epidermis
The epidermis is a single-celled layer that covers the surface of the plant and helps to protect it from physical damage and other external threats.
Both of these tissues play an important role in the health and survival of the plant.
• What is plant tissue?
• What are the different types of plant tissues?
Complex tissues are composed of several types of cells that work together to perform specific functions. Examples of complex tissues are xylem and phloem, which transport water and nutrients throughout the plant, and the vascular cambium, which helps with the growth and expansion of the plant.
• What is the function of plant tissues?
• How do plant tissues interact with each other?
Additionally, the vascular tissues of plants form a continuous system that helps transport water, minerals, and organic compounds throughout the plant. Signal molecules, such as hormones, can also be exchanged between different tissues and help regulate the development of a plant.
• What are the differences between plant and animal tissues?
Another major difference between the two is the presence of chloroplasts in plant cells. Chloroplasts are organelles that contain chlorophyll, which is responsible for photosynthesis. This process gives plants the ability to make their own food, while animals must rely on a food source to obtain energy.
• What are the benefits of plant tissue culture?
Additionally, it allows for plants to be cloned, meaning that desirable traits can be replicated. Finally, it enables plants to be genetically modified, which helps to produce plants with desired traits and characteristics.
• What are the challenges of plant tissue culture?
Additionally, the explants need to be kept in specialized equipment with adequate humidity and temperature control to maintain their growth, which can be difficult and costly to achieve.
Finally, the laboratory techniques required to successfully culture explants are often very complex and require specialized knowledge and experience to carry out.
• What are the applications of plant tissue culture?
Plant tissue culture has been used to produce large numbers of clonal plants with desirable traits, such as disease resistance, drought tolerance, and improved yield, which can then be used to help improve the quality and quantity of agricultural crops.
Plant tissue culture can also be used to produce secondary metabolites, such as pharmaceutical compounds and natural fragrances, for medical and cosmetic purposes. Plant tissue culture can also be used to conserve endangered species, as plant tissue can be stored and regrown in the lab, helping to ensure the survival of rare species.
Finally, plant tissue culture can be used in bioremediation, which is the use of living organisms to remove pollutants from contaminated environments.
• What are the safety guidelines for handling plant tissues?
These guidelines include wearing protective clothing such as gloves and a lab coat, washing hands often, and disposing of contaminated clothing and equipment properly. It is also important to keep the work area clean and organized, and to avoid contact between plant tissues and other objects or people. Working with sterile equipment and materials can help reduce the risk of contamination.
Additionally, it is important to avoid cross-contamination by using separate tools for each plant tissue sample and by disposing of used tools and materials properly. Following these guidelines can help ensure a safe and successful experience when handling plant tissues.
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