Plant Kingdom | Classification, Characteristics, Life cycle, Example,

Hello friends, in today’s article, we are going to study thoroughly about the plant kingdom and will learn in very simple language. In this, you will get all the information related to the Plant kingdom or Botany, but this article will have to be read from beginning to end. Only then you will understand well, so let’s read step by step without wasting time.

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Who gave the plant kingdom?

Scientist Carolus Linnaeus was the first to present the Plant kingdom, he was the first to classify the organisms, in which he divided the organisms into two kingdoms.

  1. Kingdom Plantae
  2. Kingdom Animalia

He classified the organisms on the basis of the cell wall. This means those which had cell wall were kept in the Plant kingdom and those which did not have cell wall were kept in the Animal kingdom.

they made an artificial classification.

What is artificial classification?

When an organism is classified on the basis of some external morphological features, then such classification is called artificial classification. For example – leaves, color, shape, etc.

This classification was wrong because it was classified only on the basis of external symptoms which is not correct. Now another classification system came to rectify this, which was named the Natural system of classification.

What is the Natural system of classification?

When organisms are classified on the basis of external and internal characteristics, such classification is called the natural system of classification.

This classification was largely explained by the scientists George Bentham and Joseph Dalton Hooker. There was also a shortcoming in this classification, to fulfill which another classification came, whose name phylogenetic system of classification.

What is the Phylogenetic system of classification?

When classification is done on the basis of phylogenetic relationships along with internal and external characteristics, then such classification is called phylogenetic classification.

What is the Phylogenetic relationship?

On the basis of ancestry, the relation which is seen whose ancestors are closer, then this relation is called a Phylogenetic relationship. Like our ancestors show more relation with Apes (Chimpanzee).

Characteristics of the plant kingdom –

  1. They are multicellular and eukaryotic. There are some exceptions in these, that is, there is also a single cell.
  2. Their growth is uncertain.
  3. A low level of sensitivity is also found in these. For example – the plant of Chui Mui.
  4. In these, the cell wall is made of cellulose.
  5. They are autotrophic/photosynthetic producers.
  6. These are of both terrestrial and aquatic types.
  7. Food is stored in them in the form of starch.
  8. There are both types of asexual reproduction and sexual reproduction.
  9. Generation alternation is found in them.
  10. Theophrastus is the father of botany.
  11. They get their nutrition by photosynthesis because they have Chloroplast in their cell.

But there are some plants that are heterotrophic. They get their nutrition from insects like – Utricularia (Bladderwort), and Venus fly traps. You may have seen some flowers in movies or videos that when insects sit on those flowers, the flower closes and insects get trapped inside it. After which these flowers get nutrition by decomposing these insects.

Classification of the plant kingdom –

Scientist Eichler has divided the plant world into two parts.

  1. Cryptogamous
  2. Phanerogamous

What are cryptogamous?

Seedless plants have been kept in this group, that is, in which seeds are not found. This group is divided into three parts.

  1. Thallophyte
  2. Bryophyte
  3. Pteridophyte

Characteristics of Thallophyte (Algae) –

  1. The study of algae is called Phycology/Algology.
  2. Algae are found in the Monera kingdom, Protista kingdom, and Plant kingdom in all three kingdoms.
  3. Their body is called a thallus. See what is Thallus, when the plant body is not differentiated into root, stem, leaves, fruit, and flower, then it is called Thallus.
  4. It is aqueous. They are found in both sea and fresh water.
  5. They are also single-celled. Like – Chlamydomonas.
  6. They live even after forming a colony. Like – Volvox
  7. They are also fibrous like – Spirogyra, Ulothrix, etc.
  8. There are both types of asexual reproduction and sexual reproduction.
plant kingdom Chlamydomonas

Asexual reproduction –

In asexual reproduction, fission and sporulation take place and spores can be of two types. Non-motile spores and motile spores. This reproduction consists mostly of motile spores. Those in which flagella are found are called Zoospore/motile spores because they move with this flagellum and those in which flagella are not found are called Conidia/non-motile spores.

Sexual reproduction –

Gametes are formed in sexual reproduction and these gametes are of three types. Isogamete, Anisogamete, and Oogamete.

Isogamete – Such gametes which have the same shape and size are called Isogamete. These gametes are of two types. Flagellated Isogamete like – Spirogyra, and Chlamydomonas and Unflagellate Isogamete like – Ulothrix

spirogyra, Plant kingdom
Spirogyra

Anisogamete – Such gametes which have the same shape but are unequal in size, then such gametes are called anisogamete. Like – Udorina

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Oogamete – Such gametes whose shape and size both are unequal are called Oogamete. In this, the small gamete is the male gamete and the large gamete is the female gamete. such as Volvox, fucus.

Classification of algae –

Algae are mainly divided into three parts on the basis of pigments or colors.

  1. Green Algae/Chlorophyceae)
  2. Brown Algae/Phaeophyceae)
  3. Red Algae/Rhodophyceae

Chlorophyll-a and beta carotenoid are found in all algae. These are of different colors because different pigments are found in them.

Green Algae/Chlorophyceae) –

  • Chlorophyll-a and Beta Carotenoid are found in it, along with it, chlorophyll-b is found, and these chlorophyll-a and b are in such a large amount that they turn green in color. These chlorophylls are found in green leaves.
  • In these, food is stored in the form of starch and the place where this starch is stored is called pyrenoid.
  • In these, the cell wall is divided into two layers. External layer and internal layer. The outer layer is made of pectose and the inner layer is made of cellulose.
  • In these, the flagella are uniformly found on the top of the motile spores. Whose number can be 2-8.
  • Examples – Chlamydomonas, Volvox, Ulothrix, Spirogyra, Chara, etc.
Volvox, plant kingdom
Volvox

Brown Algae/Phaeophyceae) –

  • It contains chlorophyll-a and c. Carotenoids are also there. Along with this, there is another pigment named Fucoxanthin and this pigment gives brown color.
  • These are mostly found in the sea.
  • Their size and shape are mostly fibrous. This fiber is of two types. One simple fibrous and the other dense fibrous. Simple filamentous means they have fewer filaments like – Ectocarpus and dense filamentous means they contain many filaments like – kelp and this kelp alga is hundred-hundred meters long.
  • Food is stored in them in the form of laminar and mannitol. It is a type of carbohydrate.
  • A phycocolloidal substance is found outside their cell wall which is called algin. It is used in making paint, and polish.
  • The spore formed in their asexual reproduction is pear-shaped; in this spore, two flagella have come out from the unequal side.
  • The gametes formed in their sexual reproduction are also pear-shaped.
  • Their body or thallus is haploid. Only Fucus is diploid.
  • Examples – Dictyota, Ectocarpus, Laminaria, Sargassum, and Fucus.
  • Sargassum is used as food.

Red Algae/Rhodophyceae –

  • It contains chlorophyll-a and d. Carotenoid is also there, it also contains another pigment named Phycoerythrin and this pigment gives the red color to this algae.
  • It is mostly found at the base of the sea and the water here is warm.
  • In these, food is stored in the form of Floridian starch, which has a similar structure to glycogen and amylopectin.
  • The spores that are formed in their asexual reproduction are non-motile.
  • The gametes produced in their sexual reproduction are also non-motile.
  • Examples – Gelidium, Gracilaria, Chondrus crispus, Polysiphonia, Porphyra, etc.

What are bryophytes?

  1. These are found in moist, shady places on the hills, and when plants are found in such places, they are called Sciophytes.
  2. They are called the amphibians of the plant kingdom. Why is it called it is the first terrestrial plant, when they make gametes, their gametes go into the water and fertilize there and the new organism that is formed after fertilization comes back to the land. It means that their life is on the ground but it is also dependent on water.
  3. Their body is thallus, and this thallus is haploid.
  4. In their thallus, a root-like structure emerges, which is called a root.
  5. Their main plant body is called gametophyte.

The life cycle of Bryophytes –

Their male gametophyte has a male reproductive organ called antheridium and the female gametophyte has a female reproductive organ called archegonium both these structures are multicellular and each of their cells is haploid.

Now both of them will make male and female gametes, the male gamete is called Antheridia and the female gamete is called Egg. Both these gametes are haploid. The Antheridia is biflagellate. This antheridium reaches the archegonium through water, after which fertilization starts and after fertilization, the zygote is formed.

This zygote is diploid. After that, this zygote undergoes continuous division to form a structure called the sporophyte. This sporophyte remains attached to the gametophyte and receives nutrition from it as it cannot photosynthesize.

This sporophyte has three parts. Foot, Seta, and capsule, foot helps in adhesion and the seta serves to send nutrition to the capsule because there are many diploid cells in the capsule. These diploid cells are called spore mother cells.

These mother cells will undergo meiosis to form another new haploid structure called a spore. They have some structures called Cletus which absorb water from the environment due to which the capsule bursts and the spores come out. Now, these spores come out and divide continuously to form gametophytes. This process will go on again and again and bryophytes will increase their number.

Classification of Bryophytes –

There are two types of bryophytes.

  1. Liverwort (Hepaticopsida)
  2. Moss (Muscidae)
Liverwort (Hepaticopsida)Moss (Muscidae)
In this, the gametophyte is formed by direct germination from the spore.In this, the gametophyte is formed by indirect germination i.e. after the spore first filament (Protonema) is formed, and this filament further forms the gametophyte.

Liverwort (Hepaticopsida) –

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Their gametophyte structure is similar to the liver, hence called liverwort.

Prime example – Marchenshia.

They reproduce asexually under adverse conditions and in asexual reproduction, they form a cup-like structure called a gemma cup on this cup a green multicellular structure called gemma is formed and it grows out of which some parts break off and falls to the ground and this broken part grows to form a gametophyte.

In this, the sporophyte is completely parasitic on the gametophyte.

Moss (Muscidae) –

In this, there is indirect germination.

Its sporophyte is semi-parasitic on the gametophyte because its sporophyte does photosynthesis. Due to this it prepares food but remains attached to the gametophyte for shelter.

Examples – Funaria, Polytrichum, Sphagnum, etc.

What are pteridophytes?

  1. These are used as decorations.
  2. From the point of view of development, these are the first terrestrial plants.
  3. First of all, vascular tissue came in these.
  4. Their main plant body is sporophyte and their main plant body is differentiated into root, stem, and leaf.
  5. They were meeting effectively 350 million years ago, that is, they were meeting in very large numbers.
  6. They are called reptiles of the plant kingdom. Why is it said because on the basis of the origin of development fishes → amphibians → reptiles came first? So they came after amphibians, that’s why they are called reptiles, not creeper organisms.
  7. These have also been found on the ground, but they also depend on water.

The life cycle of Pteridophytes –

Their main plant body is called sporophyte and this sporophyte is diploid, two types of leaves are found on them and these two leaves perform different functions and on the basis of function, they also have different names. Or it is called Tropophyll, and it is related to photosynthesis the other leaf is called Sporophyll.

This leaf is related to reproduction. On this sporophyll, there are sporangia and inside this spore bag, there are cells which are called spore mother cells. All these cells are diploid, now these cells produce many haploid spores by meiotic division, due to which the sporangium bursts, and these spores fall outside on the ground.

After that, it divides continuously to form a small structure called gametophyte or prothallus. In this gametophyte, both anther and pistil are found. From this anther, the pistil goes through the water to the archegonium of another gametophyte, fertilizes the egg, and forms a diploid zygote, and this zygote develops into an embryo, and this embryo develops into the ground and develops into the main plant body (sporophyte) in this life. Isospores are present in the cycle, hence it is called homospory.

Another life cycle of pteridophyte –

There are two types of sporophytes in it and both sporophytes have different types of leaves. The leaf of a sporophyte is called a microsporangium and on this leaf, there is a microsporangium and inside this microsporangium, there is a microsporangium mother cell.

Meiosis takes place in this cell as a result of which spores are formed and these spores are called microspores. Microspore is called because it is smaller than the megaspore, after that when there are many microspores, the sporangium bursts, and microspores come out.

Now this microspore further develops into a gametophyte and in this gametophyte, only anther is found, hence it is called a male gametophyte.
The leaf of the second sporophyte is called the megaspore leaf because on this leaf there is a megaspore receptacle and inside this megaspore receptacle there is a megaspore mother cell.

Now meiosis takes place in this cell, as a result of which spores are formed and this spore is called a megaspore, it is called a megaspore because it is bigger than the microspore, after that when there are many megaspores, the megaspore bursts, and megaspore comes out. Is.

This megaspore further forms gametophyte and in this gametophyte, only archegonium is found, hence it is called the female gametophyte, after the male gamete goes to the female gamete through water, after fertilization the embryo again forms sporophyte. Now you have seen that in this life There are unequal spores in the circle, hence it is called heterospory.

Example – Selaginella and Salvinia.

Salvinia natans plant kingdom
Salvinia natans

Classification of Pteridophytes –

Pteridophytes are divided into four groups.

Psilopsida –

All the plants of this group have become extinct except one, whose name is celom, it is also called a living fossil.

Lycopsida –

Two examples of this class are Selaginella and Lycopedium.

Selaginella, plant kingdom
Selaginella

Sphenopsida –

This class is also called horsetail because the leaves of the plants of this class come out like a horse’s tail, for example – Equisetum mostly because of this, there is a fire in the forest.

How does fire occur in forests – Silica is found in their leaves and stems and when their leaves and stems collide with each other, a spark comes out due to the friction of silica and silica, which causes fire.

Tiropsida –

The ability to bear seeds was first seen in this, fern has been placed in it.

Examples – Dryopteris, Adiantum, Terris

That’s it, now our next point about cryptogams –

What are Phanerogams?

Seeded plants are kept inside it. This means in seeds are found. It is divided into two parts.

  1. Gymnosperm
  2. Angiosperm

Characters of Gymnosperm –

  • There is no cover on their seeds, hence they are called gymnosperms.
  • They do not have flowers or they are non-flowering.
  • Their main plant body is sporophyte which is diploid.
  • Their body is differentiated into stem, leaf, and root.
  • Stem – In these, the stem can be in the form of shrubs and can also be in the form of a tree, but mostly it is in the form of a tree. Their stem can be branched as well as unbranched. Branched occurs in Pinus and unbranched occurs in Cycas. The tallest Gymnosperm is Sequoia.
  • Root – There are two types of roots in these.
  • Fungal root (Mycorrhiza) – There are some trees whose roots show a symbiotic relationship with fungi, that is, by absorbing water and minerals, for example – Pinus, in which fungal roots are found.
  • Coralloid root – In this, blue-green algae show a symbiotic relationship, they do nitrogen fixation. Example – Cycas
  • They have taproots.
  • This Gymnosperm is mostly found in cold areas or where there is less water, so their leaves are small and needle-like, on which a layer of wax is covered, which is called the cuticle, and there are small holes in this cuticle, which are called the cuticle. It is called Stomata.
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The life cycle of gymnosperm –

  • In this, the life cycle is mostly heterosporous.
  • In this too, there are two types of sporophytes and both sporophytes have different types of leaves. The leaf of a sporophyte is called a microsporangium and on this leaf, there is a microsporangium and inside this microsporangium, there is a microsporangium mother cell.
  • Now meiotic division takes place in this cell as a result of which spores are formed and these spores are called microspores. In this, this microspore germinates or develops inside the sporangium and a cover is placed around this spore, then this structure is called male gametophyte.
  • This male gametophyte is called pollen grain and the nucleus inside it is called the male gamete, it contains only one male gamete.
  • The leaf of the second sporophyte is called megasporangium because on this leaf there is megasporangium, it is also called ovule and it later forms the seed. This seed is not covered in any way, which is why it is called the gymnosperm.
  • This means this ovule is naked, inside this ovule there are two coverings and inside it, there is a tissue which is called the ovule body and in this ovule body, there was a big cell which is called the megaspore mother cell.
  • Meiosis takes place in this cell and four megaspores are formed out of which three are destroyed and one megaspore remains which is haploid. This megaspore divides continuously to form a group of megaspore cells which is called Embryosac.
  • It is also haploid, there can be one or more than one of these cells, whose size is slightly larger than other cells, which are called egg cells. This egg cell is inside the endosperm. That’s why the endosperm is called female gametophyte.
  • Now pollen grain comes in it through wind, after that pollen tube is formed from which a male gamete goes and once fertilization takes place and the zygote is formed.

The character of angiosperm

In these also the main plant body is sporophyte.

There is a covering over their seeds, hence they are called angiosperms. Aavrit means to cover. It is floral.

The life cycle of angiosperms –

They are floral and if we talk about the structure of their flowers, then these flowers are on inflorescence which is made up of four parts.

angiosperm mature flower
Image credit – Wikipedia.org

Gynoecium – It is made up of pistil/carpel and pistil is made up of three things. Stigma, style, and ovary.

Androecium – It is made up of Stamen and Stamen is made up of two things. Anthers and filaments. This stamen is also called microsporangium leaf because stamen is a modified form of microsporangium leaf and this stamen has four microsporangia.

And inside each microsporangium, there is a microspore mother cell and meiotic division take place in these, which makes a microspore tetrad and this tetrad is covered with callose. The small spore inside it breaks free and divides inside to form a pollen grain, which consists of two generative cells and a vegetative cell, out of which two generative cells are called male gametes and this three-cellular structure is called male gametophyte.

Calyx – It is made up of sepals.

Corolla – It is made up of petals.

Together these four structures are called floral leaves.

In this, the megaspore gets transformed into the pistil and inside this pistil, there is a sporangium which is called the ovule and this ovule later develops into a seed. It is covered with a cover, hence it is called angiosperm.

Inside this ovule, there are two coverings and inside it, there is a tissue which is called the ovule body in this ovule body, there was a big cell which is called the megaspore mother cell. Meiosis takes place in this cell and four megaspores are formed out of which three are destroyed and one megaspore remains which is haploid.

Now the haploid nucleus inside it divides to form 2 to 4 to 8 nuclei, out of which two nuclei come together in the middle and these nuclei are covered with a cell wall, now eight nuclei become seven cells. The whole structure is called Embryosac.

It contains an egg or female gamete, hence it is also called the female gametophyte, after a male gamete or pollen grain comes, germinates, and after a pollen tube is formed and two male gametes come inside this pollen tube. One of the male gametes fuses with the egg to form a zygote.

And the second male gamete in the middle of which the two nuclei are together is called the primary endosperm nucleus. By fusion with it, a triploid cell is formed which is called a primary endosperm cell. This endosperm nourishes the zygote. After this, the main plant body is formed.

Some important questions and answers are given in the article.

What are some characteristics of the plant kingdom?

What are the five subgroups of the plant kingdom?

Plant kingdom classification?

Is the plant kingdom autotrophic or heterotrophic?

Plant kingdom examples?

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