Notes of class 8 : Reproduction in plants

Reproduction :- Reproduction is the process in which every living organism produce their own kind.

Significance ( importance ) of Reproduction :- 

• Reproduction multiplies number of individual of a population.
• Reproduction maintain continuity of life on earth. 

Modes of reproduction in the plants :- Plants reproduce by following three methods :

1. Asexual Reproduction
2. Sexual reproduction
3. Vegetative propagation ( reproduction )

Characteristics of Asexual reproduction :-

• In asexual reproduction only one parent member is required.
• During asexual reproduction there is no formation of gametes ( single sex cell ).
• For asexual reproduction in plant body there is formation of some special asexual structures like spores, bud, conidia etc.

The plants perform asexual reproduction by following methods :-

(i) Binary Fission :- 

• In binary fission an individual divides in to two identical daughter cells.
• In binary fission at first nucleus divide in to two parts ( Karyokinesis ) it is followed by division of cytoplasm ( Cytokinesis ).
• The binary fission is visible in unicellular organisms like bacteria, unicellular algae and fungi.

(ii)Budding :-

• In budding a small out growth develop on the body of parent. It is called bud.
• The bud contains small part of nucleus of parent .
• Bud separate from parent body after some times and grow as new individual.
• Unicellular fungus Yeast is best example of budding process.

(iii)Fragmentation :-

• Fragmentation method of asexual reproduction is commonly reported in filamentous algae spirogyra in which the cells are arranged in linear manner.
• From body of mature spirogyra few linearly arranged cells split and after some time find its attachment on submerged rock. This cell is called hold fast.
• The hold fast ( basal cell ) starts the cell division and grow as new spirogyra.

(iv)Spore formation :-

• Spores are the special structure develop on the body of parents for asexual reproduction under unfavourable conditions.
• Spores are microscopic, thick walled, resistant structure.
• Spores develop in the special structure called sporangia ( sing. sporangium ).
• Fungi like Rhizopus ( bread mould ) show asexual reproduction by this method.
• Mature Rhizopus spread spores in air and these spores grow under favourable conditions of food, temperature.