Plant Tissues Xylem, Phloem, Phloyem, Xylem, Plant Tissues

In this article, along with the structure of living organisms, we will know about the tissue in detail. Know about what is plant tissue and what are its types. Also understand Permanent Tissue and Complex Permanent Tissue. What is Xylem? What is Phloem? What is the difference between xylem and phloem? What is Special Permanent Tissue, what are its types and how is it helpful for plants? We will talk about what are Laticiferous glands and how they are formed etc.

What is Tissues

In multicellular organisms, a group of cells with similar origin, structure and functions are organized to perform various bodily functions. This special group of cells called tissues are responsible for a certain function. The word tissue was first used by Witchet. The branch of biology that deals with the study of tissues is called histology.

Different cells combine to form tissue. The group of tissues together form the organ, the group of organs form the organ system and the non-system together run the life process of the organism smoothly.

This organization of multicellular organisms is of different types in plants and animals.

As we know that plants are also alive, and they also have the basic needs of life, for the fulfillment of which they have many types of functions. But the body of plants and the activities in the body are completely different from those of animals. Therefore, plant tissues are also different from animal tissues which are adapted for the processes taking place in their body.

photography of plants — Photo by Daniel Frese on Pexels.com

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Xavier Bichat introduced the term tissue during the study of anatomy in 1801. Bichat identified 21 types of primary tissues that make up the parts of the human body.

Plant and Animal Tissues

Meristematic Tissue – Immense ability of division is found in these.
Permanent Tissue – They perform a variety of functions by losing the ability to divide.

Permanent tissue is further divided into two types on the basis of the complexity of their structure-

Simple Permanent Tissue
Complex Permanent Tissue

Simple permanent tissues can be further divided into three parts on the basis of their cell tendencies and intracellular recesses-

Parenchyma
Cholenchyma
Sclerenchyma

Similarly, complex permanent tissues are also of two types on the basis of the functions performed by them-

Xylem
Phloem

Similarly, animal tissues can also be broadly divided into four parts-

Epithelial Tissue
Connective Tissue
Muscular Tissue
Nervous Tissue

What is Plant Tissue?

Plant tissues are of two types, meristematic tissue and permanent tissue.

Meristematic Tissue

The cells of this tissue have a tendency to divide rapidly. These tissues are found in the growing parts of plants, such as the apical rogion of the stem and roots. These tissues are responsible for increasing the length and thickness of plants. It is mainly of three types:

Apical Meristematic Tissue

This tissue is found in the root and tip of the stem and in the buds located in the chambers of the leaves. These tissues are mainly responsible for increasing the length of plants. Example – shoot head and root head

Lateral Meristematic Tissue

These tissues are found in the lateral parts of the stem and roots of plants, which is of special importance for the thickness of the plants. In this vascular system like xylem and phloem are found. Example – convection cambium and cork cambium

Intercalary Meristematic Tissue

These tissues are always found at the nodes and due to these tissues the plants increase in length. These are actually the remnants of the apical meristems, which are separated due to the advent of permanent tissues in between. When grasshoppers are eaten by herbivorous animals, it grows only through interstitial meristems.

Permanent Tissue

The meristem tissue gets converted into permanent tissue when it matures. But permanent tissues do not have the ability to divide. The cells of these tissues are dead or living, thin or thick walled. It is of three types:

Simple Permanent Tissue

The characteristic of this tissue is that it has the same type of shape and a group of homogeneous cells performing the same type of function. These are of three types:

Parenchyma

These tissues are found in the soft parts of plants and various organs (outer skin and fruit pulp etc.). Its main function is to store food items like starch, protein and fat. The fleshy stems and leaves of some plants like hawthorn and euphorbia act as water storage. If green salts are present in them, they undergo photosynthesis and are called chlorenchyma.

Collenchyma

This tissue is a modified form of softwood and is found under the outer skin of herbaceous plants and in the petioles of leaves. Its cells are living, vacuole and cytoplasmic. Its cell walls are unevenly thick due to the deposition of cellulose and pectin at the corners. Its main function is to provide mechanical strength and flexibility to plants and to perform photosynthesis in the presence of chloroplasts.

Sclerenchyma

This tissue is dead, long, narrow and sharp at both ends, containing thick cell wall and lignin. This tissue provides mechanical strength to the plants. There is no deposition of cellulose at many places in its cell wall as these places contain protoplasmic filaments. Such places are called simple pits. Due to the presence of lignin, its fibers are very strong, which are called sclerids. These tissues are found in the inner fruit walls of walnuts and coconuts and in the seeds of Leguminosae family.

Complex Permanent Tissue

This type of tissue is made up of more than one type of cells. It is also called vascular tissue because in plants it performs the function of conduction. It includes vascular tissues like xylem and phloem.

What is Xylem?

They extend from the roots of plants to the leaves in the form of thin and long tubes. It serves to transport water and mineral-salts absorbed by the roots to the leaves and gives strength to the plants, it is also often called wood. Xylem is called complex tissue because it is made up of four types of cells – tracheids, vessels, wood fibers and wood parenchyma.

Vessels and vessels are made up of dead cells. The vessels are absent in pteridophytes and gymnosperms.

It has many vessels and vessels for the transport of water and mineral salts present in the angiosperms. The woody senescence (living and abundant) under the xylem helps in the accumulation of starch and fatty substances and transport of water. Its cell wall is hard and lignin-rich, which provides additional mechanical strength to the plants. Collectively it is called Xylem Fibre.

What is a Vascular Bundle?

Convection pool is made up of xylem and phloem with or without cambium. Convection pools containing cambium are called open vascular bundles, whereas vascular pools without cambium are called closed vascular bundles.

Endarch Centrifugal xylem (when the protoxylem is towards the middle and the metaxylem is towards the outside).

Exarch centripetal xylem (when the protoxylem is outwards and the metaxylem is towards the centre).

Joint vascular bundle The xylem and phloem are found side by side on a radius.

Concentric is one type of vascular tissue, which surrounds another type of vascular tissue.

secondary growth

When the plant is small, then the tissues in it are formed by primary meristem i.e. the tissues formed by them are called primary tissue.

With age, new cells are formed in dicotyledonous plants from new meristems produced by permanent senescence. These new cells are called secondary tissues.

Due to these secondary tissues, the plant organs increase in thickness, which is called secondary growth.

Secondary growth is due to cambium and cork cambium. Secondary growth is found only in dicot plants. The age of the trees is determined on the basis of the annual rings formed by it.

What is Phloem?

The transport of food produced in photosynthesis to different parts of plants is carried out by the phloem vascular tissue.

It is made up of four types of cells – sieve tubes, companion cells, phloem parenchyma and phloem fibres.

Of these, the perforated wall in the sieve tube mainly performs the function of transporting the food material, while the rest of the cell assists it in this function. The tubules of the phloem are living cells and do not contribute significantly to the mechanical strength of plants. The sieve tubules become enucleate at the mature stage. These cells are absent in the gymnosperm.

What is the difference between Xylem and Phloem?

Tissues of xylem are tubular shaped structure, in which there is absence of cross walls. This tissue resembles the shape of a star. Whereas phloem tissue is tubular shaped, elongated, having structures with presence of walls with thin sieve tubes.
Xylem is a vascular tissue that absorbs water and dissolved minerals from the root and transports it to the rest of the plant and Phloem is a vascular tissue that transports soluble organic compounds produced during photosynthesis from the green parts of the plant to the rest of the plant. Is.
The xylem is mainly located at the center of the vascular bundles and the phloem is mainly localized towards the periphery of the vascular bundles.
The fibers of xylem are short and the fibers of phloem are large.
Xylem is present in roots, stem and leaves and phloem is present in stem and leaves, which later transfer and develop into roots, fruits and seeds.
The movement of xylem is in one direction i.e. unidirectional up, while the movement of phloem is in both the direction (Up and Down).
Xylem includes Tracheids, Vessel Elements, Xylem Parenchyma, and Xylem Fibers. Wherein phloem includes: Companion Cells, Sieve Tubes, Bast Fibres, Phloem Fibers, and Phloem Parenchyma.
Cells of xylem tissue are dead cells except parenchyma cells and cells of phloem tissue are living cells except bast fibers.
Cell wall of cells in xylem is thick and cell wall of cells of phloem is thin.
Lignified cell wall is present in xylem and cell wall is not lignified in phloem.
The amount of xylem tissue in vascular bundles is more than that of phloem tissue i.e. the amount of phloem tissue in vascular tissue is comparatively less.
Water and minerals are carried from the roots of the plant to its leaves through two types of elements of xylem tissue i.e. Xylem Vessels and Tracheid and the living cells of the phloem are called ‘Sieve Tubes’. ) are called. The sieve plates are found on the end wall of the cells in the phloem, in which small pores are made.
The xylem transports soluble mineral nutrients and water molecules from the roots to other parts of the plant and the phloem transports food and other nutrients including sugar and amino acids from the leaves to the storage organs and growing parts of the plant.
Xylem provides mechanical strength to the plant and helps the stem to stay strong while circulating sugars synthesized by the photosynthetic regions of plants for storage of organs such as roots, bulbs and tubes. Is.
Xylem replenishes the total amount of water molecules lost through transpiration and photosynthesis and is responsible for transporting proteins and mRNAs throughout the plant.

Special Permanent Tissue

Epidermis This is the outermost layer of the plant body, which mainly performs protective functions. It prevents excessive water loss by transpiration from normal shoots of plants. The reason for this is the accumulation of a hard substance called cutin or suberin on the outer surface of the epidermis, which reduces the water loss in the process of transpiration in plants.

The epidermis of stomata branches has tiny tiny pores called stomata, which are surrounded by bean or kidney-shaped epidermal cells called guard cells. Door cells are living, chloroplast and centralized. The gate cells and the surrounding extracellular cells together form the stomatal complex.

The skin follicles of the epidermis are unicellular or multicellular, branched or simple. If skin follicles perform the function of secreting, then they are called glandular follicles, it is of two types

The stinging follicles present on the outer skin secrete toxic substances, such as scorpion plant nectaries, secretes sugar-like substance nectar. The digestive glands of insectivorous plants secrete proteolytic enzymes.

Internal glands These are found inside the tissues. Under this, oil glands in the peel of lemon and orange fruits and mucous secretory glands in betel leaves, resins and tannins secreting glands are found in Pinus. Hydethodes are glands that secrete water.

Laticiferous glands Glands cells are elongated, thin walled, multinucleated, filled with rhubarb in some cells containing thick liquid latex. These cells are branched and multinucleated with thin walls and in the form of independent units such as rhubarb cells in Euphorbia, Madar and Kaner.

In poppy, rubber, rhubarb vessels are found, which are formed by the union of many cells and the dissolution of the layers of the seed.

Important facts related to tissue

In fact, wood is the secondary xylem, which is formed as a result of the activation of the vascular pathway during secondary growth.

Secondary growth in the stems and roots of plants occurs as a result of the activity of convection adha and cork atha.

Secondary growth refers to new meristems produced by permanent parenchyma tissues in the stems or roots of plants, resulting in an increase in the length and thickness of the plants. This growth is found only in dicotyledonous plants, as they are found in the same, whereas it is lacking in monocotyledonous plants. Cork is a thick walled dead cell that forms a layer on the periphery of the stems of plants.

The cork acts as a protection for the tissues. Commercially, cork is produced from a tree called Curcus subarna.

Tags: Phloem, Phloyem, Plant Tissues Xylem, Xylem