Tissues in Plants – Plants are composed of cells which then form tissues. Tissue itself is a group of cells that have the same structure and function and are bound by material between cells to form a single unit. The initial formation of plants begins with meristem tissue. Check out a more complete explanation of the following tissues in plants, Sinaumed’s:
Tissue Functions in Plants
Meristem tissue is divided into various groups called simple networks. This simple tissue consists of cells with the same structure as parenchyma, collenchyma, and sclerenchyma. The meristem tissue will then actively divide through the process of mitosis.
In understanding tissue in plants, there is a tissue culture method that is used to isolate parts of appendages, there is an underlying theory and there is much more that you can learn in the Textbook of Plant Tissue Culture by Noor Aini Habibah, Enni Suwarsi Rahayu, & Yustinus Ulung Anggraito .
The ability of continuous cell tissue causes an increase in new cells continuously so that cells experience changes in cell properties and differentiation. In addition, the consequences of this cell division will also form various complex tissues that do not have the inability to divide again or become non-meristematic tissues. Know the function of the following tissues in plants, Sinaumed’s:
- Protects the body parts of plants
- Helping the process of growth and development of plants
- Strengthens the plant body
- Help circulate food essences or substances found in plants throughout the body
- Helps store food reserves in plants
- Supports all activities in plants
Those are the functions of the tissues in plants. In the following discussion, we will discuss the structure of tissues in plants.
Tissue Structure in Plants
Plants consist of two structural systems namely shoot system and root system, where shoot system consists of above-ground structures including leaves, stems, fruits, and flowers. Meanwhile, the root system consists of roots, tubers, and rhizobial structures which are located underground and are the origin of plant growth.
To understand the structure and anatomy of plants, Sinaumed’s can read a book entitled Plant Anatomy by Sri Mulyani ES which explains in detail the cell structure and function of each cell organelle in plants.
This system is structured differently, defined by sets of specialized mature cells that perform various functions ranging from protection, support, metabolism, reproduction enabling plant growth, and development. For example, plant cells are formed in meristems which multiply and grow to plant tissues. Tissue structure in plants as follows.
Meristematic Network
Meristem tissue is composed of a group of cells that remain in a period of growth and are constantly dividing. Network features include:
- Composed of young cells that are in the phase of division and growth.
- There are generally no intercellular spaces.
- Cell shape is round, oval, or polygonal with a thin cell wall arrangement.
- Each cell is rich in cytoplasm and contains one or more nuclei.
Based on the way it is formed, meristematic tissue in plants is divided into three, namely:
- Promeristem, has existed when the plant is still in the embryonic period.
- Primary meristems, actively dividing tissues, are found at the tips of stems, tips of roots, and buds of mature plants. Causes an increase in plant length.
- Secondary meristem, formed from primary meristem tissue. Causes an increase in the size of the plant body.
Based on its location, meristem tissue is divided into three, namely:
- Apical meristem, found at the tips of roots and stem tips of plants. Produces an increase in plant height and length (primary growth).
- Lateral meristem, is parallel to the circle where the organs are found. Produces secondary growth.
- Intercalary meristem, found between the segments of the stem resulting in an increase in the length of the segments of the stem.
Permanent Network
Meristem tissue which is either primary or secondary will differentiate into permanent tissue. Later, the permanent network does not grow and multiply again. Based on its function, permanent tissue in plants can be divided into several types, namely epidermal tissue, parenchyma tissue, supporting tissue (colenchyma and sclerenchyma), transport tissue (xylem and phloem), and cork tissue.
In understanding the various types of networks, you can read the book Plant Anatomy by Hasanuddin; Muhibbuddin; Wardia; Mulyadi, this book contains various cell and tissue structures as well as the anatomy of various different plants.
Epidermis Tissue (Protective Tissue)
Epidermal tissue is a tissue in plants that is located in the outermost tissue that covers the entire surface of the plant body. The characteristics of the epidermal tissue include thin, usually only composed of one layer of cells, does not have chlorophyll, the surface facing out is covered with cutin which produces the cuticle (inner layer), large vacuoles can contain anthocyanin, the arrangement of cells is tight without spaces between cells, The cell wall varies depending on the position and type of plant.
Functions of the Epidermis in Plants, including:
- Protector of All Plant Organs The most important function of the epidermis is to protect all plant organs, from stems, leaves, roots, or fruit from all conditions and influences from the external environment. The cells that are arranged in neat rows in the epidermal tissue allow the organs and parts of the plant body to be protected from changes in air temperature, humidity, direct pathogen infection, and so on. Therefore, epidermal tissue is generally characterized by a harder texture compared to other tissues. In addition, the epidermis is also equipped with fans, root hairs, and spina (thorns).
- Storage Place for Water Reserves Cells found in epidermal tissue have flat and large protoplasm. Well, this is what makes the function of the epidermis as a place to store water reserves for plants. During the dry season and when the soil water content is insufficient, the water stored in the protoplasm of the epidermal tissue will be taken and transported to the leaves to be processed through photosynthesis.
- Limiting Evaporation in Plants The next function of the epidermis is as a regulatory network for the process of transpiration or evaporation of water and plants. This function of the epidermis is carried out by stomata which are a part of the epidermal tissue besides the trichomes. When the air temperature is high, the stomata in the epidermal tissue will close tightly so that the rate of plant transpiration can be limited. Meanwhile, when the air temperature is low, the stomata will open very wide. This works so that some of the water can be wasted into the air and does not freeze in the plant tissue. The reason is, often the stromata is also a way of water secretion in plants through the process of guttation.
- Absorption of Water and Nutrients Epidermal tissue located in the roots also functions as an absorbent of water and nutrients from the soil. So the function of the epidermis here is performed mainly by trichomes which are modified into root hairs.
- Diffusion of Oxygen and Carbon Dioxide The last function of the epidermis is as a place for the process of diffusion of oxygen and carbon dioxide when plants carry out respiration and secretion of photosynthetic products. This function generally only occurs in leaves with stomata as the executing organ. Stomata on leaves that can carry out diffusion are often used by farmers to apply foliar fertilizer to their plants. Nutrients given through the leaves will be completely absorbed through the diffusion carried out by the stomata.
Parenchyma Network
Parenchyma tissue is a tissue in plants that is formed from the ground meristem and has a variety of shapes and functions. Parenchyma tissue functions include being closely related to surface epidermal cells which contribute greatly to the penetration and absorption of light and regulate gas exchange. The permeable wall allows the transport of small molecules between the cell and the cytoplasm.
The palisade parenchyma combined with the spongy mesophyll cells found beneath the epidermal tissue layer aid in the absorption of light which is used in photosynthesis Light parenchyma cells are found in wood which transport materials along plant stems Parenchyma cells are also found in good numbers in the xylem and the phloem of vascular plants, assisting in the transportation of water and nutrients.
Some are also involved in the biochemical secretion of nectar and the manufacture of secondary elements which act as protective agents from herbivore feeding. And the parenchyma cells found in root tubers like potatoes, leguminous plants, help in food storage. The characteristics of the parenchyma tissue itself include the arrangement of cells that are not tight. Not always chloroplasts. Composed of living cells. The location of the cell nucleus near the base of the cell.
Able to be meristematic because it can divide itself. Has lots of vacuoles. The cell size is large. There are many cavities between cells.
Based on its shape, parenchyma tissue is divided into:
- Palisade parenchyma, elongated and erect.
- Sponge parenchyma, its shape resembles a sponge.
- Star parenchyma, shaped like a star with interconnected tissue ends.
- Parenchyma folds, the shape of the cell wall folds inwards.
Based on its function, parekima tissue is divided into:
- Photosynthetic parenchyma, in which there are cells containing chlorophyll is called chlorenchyma.
- Food storage parenchyma. Water storage parenchyma.
- Air storage parenchyma, in which there are cells containing air cavities called aerenchyma.
- Transport parenchyma.
Support Network (Support Network)
Is a tissue in plants that have thick walls to support the plant body so that it can stand firmly. It consists of collenchyma and sclerenchyma tissues.
Collenchyma Network
Collenchyma tissue is a tissue in plants that functions as a reinforcement for plant organs that are still active in growth. Collenchyma cell structure as a long cell with a thick primary cell wall. The cell wall is usually irregular and composed of cellulose and pectin molecules at several points, they resemble parenchyma cells turning into collenchyma cells. When multiple cells accumulate, the Golgi bodies along with the endoplasmic reticulum come together to form the primary cell wall.
When two cells fuse or join, they form a thin primary wall which does not differentiate into collenchyma cells. Therefore as more cells accumulate and fuse, they then form a strong and disorganized functional primary cell wall. These newly formed cells will elongate to provide support for the plant to grow.
However, the primary wall is devoid of lignin, a polymeric organic complex that forms the strong structural network of vascular plants which gives it strong support, particularly to wood and bark and also prevents decay.
Colenchyma network functions, including:
- Being living cells in plant tissue, they provide support to the growing area of the plant. Because the cell wall lacks lignin, it remains flexible giving plant parts such as young stems, young roots, and young plastic (elastic) leaves support.
- They offer flexibility and tensile strength to plant tissue, allowing plants to bend.
- They also allow plant parts to grow and elongate.
- Collenchyma can combine with chloroplasts and carry out the process of photosynthesis.
Sclerenchyma Network
Sclerenchyma tissue is a tissue in plants that functions as a plant reinforcement consisting of dead cells. Sclerenchyma cell walls are very strong, thick, and contain lots of lignin. Based on its shape, sclerenchyma is divided into two types, namely fibers and sclereid cells. Fibers or fibers originate from meristem tissue and generally consist of long cells and cluster together to form webbing or ribbons.
An example is the midrib of banana leaves. Meanwhile, stone cells (sclereids) are sclerenchyma tissue whose cell shape is rounded with thickened cell walls. Examples are coconut shells or hard seed coats.
The characteristics of sclerenchyma tissue, including:
- Composed of dead cells.
- Contains lignin compounds, so the cells are strong and tough.
- Does not contain protoplast.
- Thick cell wall.
- Based on its shape, sclerenchyma cells are divided into: Sklereid (stone cells), dead cells, round, and hard-walled (resistant to pressure).
- Fibers (sclerenchyma fibers), long in shape, are found on the surface of the stem.
Carrier Network
Is a tissue in plants whose job is to transport substances needed by plants. The transport network consists of Xylem Network (Wood Vessels) Composed by tracheids, tracheas, xylem vessels, wood parenchyma, and wood sclerenchyma. Serves to transport water and mineral salts from the soil to the leaves. Phloem Tissue Composed of sieve cells, sieve tubes, companion cells, wood parenchyma cells, and wood sclerenchyma functions to transport the products of photosynthesis to all parts of the body.
Xylem and phloem form a vascular bundle, namely collateral vascular bundles, xylem and phloem are located side by side in a radius. Therefore, it can be said that the transport tissues in plants are xylem and phloem.
Based on the presence of cambium, collateral vascular bundles are divided into open collaterals, between xylem and phloem there is cambium. Collateral closed, between xylem and phloem there is no cambium.
Bicollateral vascular bundles, xylem flanked by phloem, lie at the same radius. Concentric vascular bundles, xylem and phloem form cylindrical rings. There are two forms of concentric vascular bundles, namely amphicribal (phloem surrounding the xylem) and amfivasal (xylem surrounding the phloem). Radial vascular bundles, xylem and phloem are located next to each other, but not in the same radius.
- Xylem vessels: Serves to transport water and minerals from the soil to the leaves through the roots. Xylem is composed of tracheids which undergo thickening, trachea, wood parenchyma, and wood sclerenchyma. That is why these vessels are commonly called wooden vessels.
- Phloem vessels: Serves to transport the products of photosynthesis from leaves to the rest of the plant body. These vessels are composed of sieve cells, sieve tubes (straight like tubes), companion cells, bark parenchyma, and wood fibers. The combination of xylem and phloem forms a network called a vascular carrier. In general, the vessels are formed by four types of bonds. Collateral vascular bundles, namely bonds composed of xylem and phloem side by side with xylem on the inside. Bicollateral vascular bundles, that is, xylem is flanked by phloem at the same radius. Radial vascular bundles, namely bonds composed of adjacent xylem and phloem but not at a certain radius, for example in roots. concentric vascular bundles,
If you want to dig more about Networks in Plants in a more comprehensive manner, have the book immediately at www.sinaumedia.com, as follows:
- Plant Pathogenic Bacteria by Lukman Hakim
2. Higher Plant Botany by Hasanuddin