Flower:

• Flowers are the reproductive organs of angiosperms (flowering plants).
• They consist of petals, sepals, stamen (male reproductive part), and pistil (female reproductive part).
• Flowers play a crucial role in sexual reproduction, pollination, and seed production.

Androecium (Male Reproductive Part of a Flower):

• The androecium is the male reproductive organ of a flower.
• It consists of the stamen, which includes the filament and the anther.
• The anther produces pollen grains containing male gametes (sperm cells).

Development of Pollen Sac:

• Pollen sac (microsporangium) development is essential for pollen grain formation.
• It involves the formation of microsporocytes, which undergo meiosis to produce haploid microspores.

Microsporogenesis:

• Microsporogenesis is the process of microspore formation within the anthers.
• It includes meiosis, microspore division, and pollen grain development.

Type of Microspore Tetrads:

• Microspores can form tetrads in various arrangements, including isobilateral, T-shaped, linear, decussate, and tetrahedral tetrads.

Pollen Grains:

• Pollen grains are vital for plant reproduction.
• They consist of an exine (outer layer), intine (inner layer), cytoplasm, and nucleus.
• Pollen grains carry male gametes (sperm cells) and protect them during pollination.
• The main function of tassels in corn cob is to disperse pollen grains. Corn cob is a bisexual plant. The corn cob has long tentacles, which help the pollen grains to spread through the flow of air.
• Gymnosperms (microsporangia) release pollen grains, and air current helps in release of pollen grain for pollination. However,pollen grains are not carried to the mouth of the archegonia. The male gametes are indeed discharged from the pollen tube, which grows from the pollen grain towards the archegonia.
• The pollen tube delivers the male gametes near the ovule leading to fertilisation.

Pollination:

• Pollination is the transfer of pollen from the stamen to the pistil of flowers.
• It can occur through various agents like wind, insects, birds, or bats.
• Pollination leads to fertilization and seed production.

Self-Pollination:

• Self-pollination occurs when pollen is transferred within the same flower or between flowers on the same plant.
• Advantages include reliability, trait consistency, and isolation from other varieties.
• Disadvantages include reduced genetic diversity and the risk of inbreeding depression.

Cross-Pollination:

• Cross-pollination involves the transfer of pollen between different flowers or plants.
• Advantages include genetic diversity, reduced risk of inbreeding depression, and adaptability.
• Cross-pollination can be facilitated by various agents and promotes population health.