Modes of reproduction in plants class 11th


Until now we have only known about sexual reproduction but that just in the humans and must have wondered about how plants are reproduced ? That is what I'm going to be clearing today in this article. I will be telling you about the modes that plants use to reproduce. 

Modes of reproduction in plants:

Reproduction is where an individual is going to produce a new individual by the formation of gametes. This is all we know about reproduction, but there is another type which is asexual type of reproduction which takes place in plants mostly of lower organisms like Fungi, Algae, etc.. 

There are two modes of reproduction in plants which are asexual reproduction and sexual reproduction. Asexual reproduction does not involve the fusion of gametes like in that of sexual reproduction. 

Asexual reproduction:

Asexual reproduction is the method of reproduction where there is no fusion of gametes, mitosis or meiosis involved. Asexual reproduction includes - binary fission, budding, sporulation and fragmentation. It involves only one parent hence also known as uniparental. Most common in single - celled organisms. 

In binary fission, the parent cells divide into two equal cells which further result in new individuals. This is seen in Amoeba and bacteria. In budding, there are small unequal buds which are called the parent cells grows and when separated it matures it forms a new individual. This is seen in yeast

Sporulation takes place where the plant produces motiles spores which will lead to formation of new individual. When the plant splits into many pieces (fragments) to form new individual is known as fragmentation. Each of these fragments grow into a new individual and grow. 

Asexual reproduction is also called as vegetative propagation as it involves the vegetative parts of the plants which are root, stem, leaves or buds. There are two types of vegetative propagation - artificial vegetative propagation and natural vegetative propagation

Natural vegetative propagation:

Methods of natural vegetative propagation takes place through stem tuber, runner and leaf. 

Stem tuber:

In potato (Solanum tuberosum) the stem which is underground produces extra branches from the axil known as axillary or extra axillary branches. The end of these branches get swollen due to the storage of starchy reserve food. These swollen tips are called stem tubers

The stem tuber shows the presence of many notches which are called as 'eyes'. These tubers are cut into pieces where each piece of tuber at least consists of one eye. These pieces are grown separately or commercial cultivation. 

Runner:

Runner is a slender, lying flat on ground (prostate), sub aerial branch which creeps in a horizontal manner on the soil. It develops from lower axillary bud and is thin, elongated, cylindrical and a wire like structure consisting of long internodes. This is produced by Cynodon and Oxalis

The runner makes sure it is spread in all the direction and produces as many as possible. These get detached from the parent plant and then continues to grow independently. 

Leaf:

In Bryophyllum plant the leaf of the plants produce small notches on the margin of the leaf which give rise to adventitious (change taking place due to external factors) buds called epiphyllous buds. These buds start to sprout and forming a leafy shoot

The sprouts fall onto the wet soil and form into a new individual. There are some species of the plant Bengonia where the buds form on the surface of the leaf. 

Artificial method of vegetative propagation:

The artificial method is very simple to understand. Methods of artificial vegetative propagation are cutting, grafting and budding

Cutting:

In order to carry out this method, the vegetative parts which are the root, stem and leaves are cut into small pieces which consist tissues of the plant body. These pieces are then placed into wet soil where they can grow on their own. This is said to be a convenient and cheap method of propagation. 

Grafting:

In this method, there is a part of a plant which has been rooted into the soil which is called the stock and upon this stock there is a part of another plant called scion which unites and continues to grow as one plant. 

Budding:

Budding can be called as a type of grafting where a single bud having a bark or living tissue of a plant is grafted onto the stock which is already rooted inside the soil. 

Significance of asexual reproduction:

There are many advantages of asexual reproduction, some of them are listed down:
  1. The characters which are economically important can be maintained for many generations by the method of grafting. 
  2. The fruit that cannot produce seed can be propagated by the method of grafting. Eg, Banana
  3. The plants which can sexually reproduce but have don't have much power to carry on this process or inactivity of seeds for long time or plants have less success rate of sexually producing an offspring can be easily multiplied. 
  4. If the parent plant has any common infection, that can also be removed. 
  5. It is a cheap and rapid method of propagation of the plants. 
  6. The effects of physio-chemical treatment and environmental variations can be studied. 

Sexual reproduction:

The process of sexual reproduction is complex and a slow process, in order to avoid confusion, I am only going to explain in brief here. The process goes through three phases - Juvenile phase, reproductive phase and flowering/breeding phase. Site for sexual reproduction is the flower

The male and the female sex organ is either produced on one individual or on different individual but of the same species. The sex organs consists of the male and females gametes by the process of meiosis. These gametes are haploid, meaning having only single set of chromosome. These two haploid gametes fuse together to form a diploid zygote which has double set of chromosomes. This zygote further forms a new offspring. 

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