Reproduction and Growth In Plants
Category : 7th Class
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.