Asexual reproduction doesn't involve the fusion of gametes. There are many types of asexual reproduction, all producing individuals that are genetically similar to one another and to the parent.


1. Binary Fission:

      Binary fission means “division into two”. it's the only and commonest method of agamogenesis. It occurs in prokaryotes (bacteria), many unicellular eukaryotes. protozoa and a few invertebrates. During binary fission in bacteria, the DNA is duplicated, then two copies of DNA are formed. The 2 copies move towards the other poles of the cell. The cytomembrane invaginates in the center and divides the cytoplasm into two. A new cytomembrane is deposited between two cross membranes. It ends up in the formation of two daughter bacteria, which grow in size and divide again.



      During binary fission in unicellular eukaryotes, the nucleus of the parent organism separates into 2 (two) (by mitosis). it's followed by the division of the cytoplasm. So two daughter cells of just about equal size are formed. Daughter cells grow in size so divide again.

     Some invertebrates reproduce asexually through binary fission. During this reproduction, the body is turned over two halves (fission) and therefore the missing body parts are regenerated in both halves. This kind of agamogenesis is common in planaria and lots of echinoderms.


2. Fragmentation:

     Ascertain worms grow to full size, they spontaneously slash into 8 or 9 pieces. Every bit (fragment) develops into a mature worm, and therefore the process is repeated. If a planarian breaks into many pieces rather than two, it'll even be called fragmentation.


3.Budding Figure:


      During this kind of reproduction, a bud develops as a tiny low outgrowth on the parent’s body. Just in the case of yeast (a unicellular fungus), a little bud is made on one side of the cell. The nucleus of the cell divides and one in every of the daughter nuclei is passed into the bud. Parent cells may form over one bud at a time. Each bud gets enlarges and develops the characteristics of the parent organism which was copied from its parent RNA. The bud may cut loose the parent body. In some cases, the buds never separate and, as a result, colonies of people are formed.

      Animals like sponges, Hydra, and corals also reproduce utilizing budding. In them, a tiny low bud is created on the side of the body by mitosis. This bud enlarges by miotic division in increases in number. It then detaches from the parent body and grows into a replacement organism.

      In corals, the buds don't detach from the parent body. Corals form big colonies because the buds grow into new organisms by remaining attached to the parent body.


4. Spore Formation:

       It's generally seen in most fungi (e.g. Rhizopus). When Rhizopus reaches the reproductive stage, its body cells form thick-walled spore sacs called sporangia (sing. sporangium).


     Inside each sporangium, a cell divides over and over and forms many daughter cells called spores. Each spore is roofed with a thick wall called a cyst and it can survive unfavorable conditions. When sporangia get mature, they burst and release spores. Under favorable conditions, the spores germinate and transform new Rhizopus.

      Under unfavorable conditions, some species of bacteria reproduce by forming spores. Clostridium and Bacillus species. The bacterial spores also are thick-walled. they're formed inside bacterial cells, so are called endospores.


5. Parthenogenesis:


      Parthenogenesis is additionally considered a kind of reproduction. It is an unfertilized egg that develops into new offspring. Some insects, frogs, and fishes reproduce by employing parthenogenesis. Similarly, queen honeybee lays eggs within the cells of a honeycomb. Many eggs remain unfertilized and turn into haploid males (drones) by parthenogenesis. At the identical time, some eggs are fertilized by male bees and these become diploid females (new queen and worker bees). 


6. Vegetative Propagation:


      When vegetative parts of plants i.e. roots, stems, or leaves produce new plants, the method is named vegetative reproduction or vegetative propagation. It occurs naturally, and may even be led artificially.


Natural Vegetative Propagation:


        Vegetative propagation takes place naturally in several forms.


1. Bulbs: are short underground stems surrounded by fleshy, thick leaves that contain stored food. Adventitious roots emerge under the bottom of the bulb while shoots emerge from the highest of the bottom. Tulipa, Allium cepa, and lilies reproduce by bulbs.


2. Corms: is a short, vertical, swollen underground plant stem that serves as a storehouse organ, nutrition that some plants used to survive winter, or other adverse conditions such as summer drought and heat. Buds are present at the highest of the corm. From a bud, the shoot grows and forms a brand new plant. Dasheen and garlic reproduce by corms.


3. Rhizomes: is a modified subterranean plant stem that sends out roots and shoots from its nodes. There are enlarged portions know as nodes on the rhizome. Buds are produced at nodes. The buds present on the side of the rhizome produce to shoot. The lower surface of the rhizome produces adventitious roots. Zingiber officinale, ferns, and water lilies reproduce by rhizomes.


4. Stem Tubers: It is a swollen stem that stores water and nutrients. There are aggregations of little buds within the kind of “eyes” along the surface of the tuber. Each bud develops into a shoot that grows upward and produces roots. Potatoes and yams reproduce by tubers.


 5. Suckers: are lateral stems near ground level. A sucker grows underground from far so turns up, producing the new plant. Mentha and Chrysanthemum reproduce in this state.


6. Vegetative propagation: by leaves isn't common and is seen in plants like Bryophyllum (Pather chat). This plant has fleshy leaves and adventitious buds are handed out at the margins of leaves. When a leaf falls on the ground, and then the buds grow into new plants.


Artificial Vegetative Propagation:

    Gardeners and farmers use artificial methods of vegetative propagation to extend the stock of a plant. the subsequent two are the foremost common methods of artificial vegetative propagation.


1. Cuttings:

     During this method, cuttings could also be taken mainly from the stems or roots of the parent plant. These cuttings must have had to a meristematic region from which growth can occur. When cuttings are placed in exceedingly suitable soil and under the right conditions (sufficient nutrients, water, and sunlight), they form roots and shoots. Roots and shoots grow and transform a plant clone of the parent plant from which the cuttings were taken. Roses, ivy, and grapevines are propagated by stem cuttings and put into the ground. Sweet potato is an enlarged root. Farmers place it in wet sand or soil until it produces several plantlets. Then the plantlets are removed and planted. This process is employed to provide many plants from one plant. All new plants are precisely the same. This artificial vegetative propagation has been very beneficial on sugar cane and grape plantations.


2. Grafting:

     In grafting, a chunk of the stem is cut from the plant and is attached to another plant with an established system. After a long time, the vascular bundles of the attached stem piece and therefore the host plant are connected to every other.


     The stem piece and therefore the plant begins to join. This method is employed to propagate many. (roses, peach trees, plum trees, watermelons, and various seedless fruits, including grapes).


Advantages and drawbacks of Vegetative Propagation of Plants:


     Plants can reproduce asexually via vegetative propagation. This method of reproduction has some advantages and downsides moreover.


Advantages:

      The offsprings created through vegetative spread are hereditarily indistinguishable. Therefore, beneficial characteristics may be preserved. In vegetative propagation, there's no need for any mechanism of pollination. It helps to extend the number of plants at a rapid rate. The organs of vegetative propagation enable many plants to leave out unfavorable conditions. Plants bearing seedless fruits are often grown only by vegetative propagation.


Disadvantages:

      The plants don't have genetic variations. Species-specific diseases can attack and this may lead to the destruction of a complete crop. 


Tissue Culture and Cloning:

       Cloning is that the latest method of vegetative propagation. During this method, identical offsprings are produced from one parent using its vegetative tissue or cell. Tissue culture is that the technique applied during this method.

      Tissues are taken from any part of the plant and are put in an exceedingly suitable nutrient medium. The tissue cells start mitosis and produce masses of cells called calluses that are transferred to another medium that contains different hormones for the formation of roots, stems, and leaves. Cell biology makes these structures and grows them into new small plants. The tiny plants are then planted in pots and so in fields.