7th Class Science Reproduction In Plants Reproduction and Growth In Plants

Reproduction and Growth In Plants

Synopsis

• The phenomenon of formation of new individuals from the existing ones to increase the population is called reproduction.

• Reproduction can be broadly grouped into two types: asexual reproduction and sexual reproduction.

• There are several methods of asexual reproduction such as fragmentation, budding, spore formation and vegetative propagation.

• Sexual reproduction involves the fusion of male and female gametes.

• New plants produced from different vegetative parts such as leaves, stems and roots is called vegetative propagation.

• A flower is a modified shoot, meant for reproduction. There are four whorls in a flower - Calyx (sepals) corolla (petals), androecium (stamens) and gynoecium (carpels) arranged on the thalamus called receptacle.

• Calyx and corolla form the accessory whorls, while androecium and gynoecium form the reproductive whorls.

• A flower is said to be bisexual when both the reproductive whorls are present.

• The study of pollen grains is called palynology.

• Pollination is the process of transfer of pollen grains from the anther to the stigma of same or different flowers. It is of two types:
• Self-pollination
• Cross pollination.

• After pollination, the pollen grain produces a pollen tube, which carries the male gamete through the style into the ovule, where it fuses with the female gamete. This is called fertilisation.

• Nature helps plants to distribute their seeds over a wide area so that at least few of them fall in places that provide the right conditions for growth. This scattering of seeds over a wide area is called dispersal.

• Plants can disperse their fruits or seeds by wind, water, animals and explosion mechanism

• Fruit is the mature ovary whereas ovule develops into a seed, the seed contains the developing embyro.