Explain sexual reproduction in plants.

Explanation

Sexual reproduction in plants `:` i. A flower is the functional unit of sexual reproduction in plants.
ii. The androecium and gynoecium are the male and female parts of the flower respectively.
iii. The female reproductive organ of a flower which gives rise to egg or female gamete is known as carpel . Ovary present at the base of the carpel contain ovules that undergo meiosis to form embryo sac.
iv. Stamen is the male reproductive part of a flower which gives rise to male gametes.
v. In sexual reproduction of plants,pollination is a major step, which involves the transfer of pollen grains on the stigma of female flower.
vi. Stigma becomes stigma of female pollination.
vii. The pollen grain germinates over the stigma and gives rise to pollen tube.
viii. Pollen tube carries two male garmetes which are released near egg cell present in the embryo sac.
ix. One male gamete fuses with a female gamete giving rise to zygote. The second male gamete fuses with two polar nuclei giving rise to endosperm. This is called as double fertilization.
x. Zygote develops into embryo and endosperm serves as a nutritive tissue for the growing embryo .
xi. After fertilization, the ovule develops into seed and ovary into fruit. Seeds fall upon the ground and can develop into a new plant under favourable conditions.