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As it allows for variation among organisms, sexual reproduction is the most common method of producing new ones. Flowering plants, or Angiosperms, require special mechanisms to reproduce successfully, including a specialised reproductive system, male and female gametes such as pollen grain and egg, and post-fertilization processes such as embryo and endosperm advancement, pollen and stigma connection. All parts of a flower contribute to reproduction, though some are sterile. To comprehend the process of procreation in plant species, we must first examine the various parts of the flower and their functional areas. So, let us investigate sexual reproduction in a flowering plant without further ado.
What is Sexual Reproduction?
The production of new organisms by combining the genetic data of two individuals with different sexes is known as sexual reproduction. In sexual reproduction, there is a reproductive cell called a gamete, which fuses to form a zygote through a process known as fertilisation. The zygote typically forms into a new person.
Furthermore, sexual reproduction allows for variation among individuals through the rearrangement of genetic information, both within and between individual people of the same generation, resulting in the possibility of an exceptional array of progeny, each with a genetic makeup distinct from that of its parents.
Sexual reproduction in flowering plants
Flowering plants reproduce sexually.
Sexual reproduction is the most common way for flowering plants, or Angiosperms, to produce new ones. It revolves around the flower of a plant, which contains male and female gametes, just like normal sexual reproduction. To comprehend the process of procreation in flowering plants, we must first examine the various parts of the flower and their functional areas.
Structure of flower
The flower structure has four reproductive parts: calyx, corolla, Androecium, and Gynoecium. Let’s look at each part.
Calyx: It is the outer edge of a flower made up of petals. They are typically green in colour, but they may be a colour similar to petals in some cases.
Corolla-It is the 2nd whorl of the flower and has many petals. They are coloured, thin, and soft, which would aid in pollination.
Androecium: Another filament makes up the male reproductive part of a flower. The androecium is made of a single unit known as the stamen. Pollen is produced here by meiosis and eventually disappears.
Anther: This is a four-lobed sac-like structure in charge of pollen formation. Microsporangia is the circumferential section of another that forms a pollen sac. Pollen grains are contained in the pollen sac.
Filament: These thread-like constructions are connected to the anther and keep it in place.
Structure of Anther
Anthers are important in sexual reproduction. Each anther is joined by two lobes containing two pollen compartments located lengthwise. This microsporangium has four layers: epidermis, endothecium, middle layer, and tapetum.
Formation of pollen grain
Pollen grains are male gametes of plants that participate in fertilisation during sexual reproduction. Pollen grains are formed in microsporangia and are monoecious due to meiosis in the mother cell.
The pollen grains are made up of three separate components. The nuclei responsible for fertilisation are found in the central cytoplasmic region. The grain wall is also made up of an inner layer, the intine, and an outer layer, the exine. The intine is made up of cellulose or hemicellulose, whereas the exine is sporopollenin.
Gynoecium
The gynoecium is the female reproductive organ constituted of the pistil and is located in the centre of the thalamus. The pistil is made up of the stigma, style, and ovary. As a result, ovules produce megaspores, which grow into female gametophytes.
The pistil is made up of three parts
Ovary: The ovary is a compartment that stores ovules (eggs) in preparation for fertilisation.
Stigma: It is connected to the carpel’s top, where pollen from those other flowers lands.
Style: The style is a long tube that helps connect the ovary to the stigma. It is in charge of transporting pollen from the stigma to the ovary and keeping the stigma in place.
Embryo
An embryo is a diploid cell that develops from a zygote. It begins to form at the hyphae end. Only after endocarp formation has begun does zygote development begin. This is because endosperm provides the nutrition required for embryo development.
The phases of embryogenesis are the same in monocot and dicot embryos. The stages of embryogenesis are referred to as embryogeny. The embryo development process begins with the fertilised egg (zygote), then progresses through the 2-cell, 8-cell, Globular, Heart-shaped, Torpedo, and mature embryo stages.
Conclusion
Sexual reproduction is the most effective method of producing new organisms by combining the genetic data of two individuals of different sexes, and it undergoes variation due to crossing over. With the introduction of new features in an organism, variation increases the living stability. And in flowering plants, there are reproductive organs called androecium and gynoecium, as well as a helping organ called the calyx and corolla. In addition, the plant has several processes for sexual reproduction, such as pollen pistil interaction, which increases flower stability. As a result, you now understand sexual reproduction, the sexual reproduction of flowering plants, the structure of pollen grains, and much more.
