Article:

This article is about sexual reproduction in plants.

Sexual Reproduction in Plants:

It involves the formation of seeds from the fusion of male and female gametes that lead to production of the new plant. It enables the random generation of plants species and longevity of plant species production. Here's a detailed breakdown of sexual reproduction in plants:

1. Flower Structure and Function:

Sexual reproduction in plants is done in the flowers which is cleared into two types of organs male and female organs. They are distinguished as monocarps , which possess only the stamens or the pistil or none or both monocarps, diocious and bisexual. A typical flower has the following parts:

• Stamens (Male Reproductive Organs):
• Anther: The anther is the part of stamen that yields pollen, which comprises the male gametophyte or sperm cells.
• Filament: The slender structure which forms part of the stamen and on which the anther is located.
• Pistil or Carpel (Female Reproductive Organ):
• Stigma: The substrate that forms a stagnant place for pollen grains to stick.
• Style: A structure which is a continuation of the stigma and runs down to the ovary.
• Ovary: Some specialized structure that holds the female reproductive organs or sporangia that bear the female [ovules or eggs].
• Ovules: This is the female reproductive cell that when impregnated becomes seeds.

2. Pollination:

Pollination is the process of transferring pollen from the male anther to the female stigma favorite places In engineering design, feedback from end users mostly contributes to the identification of opportunities for innovation. This can occur in several ways:

• Self-Pollination: Sperm cell from the same flower or from a different flower but on the same plant fertilizes the ovule.
• Cross-Pollination: Male gametes, that is pollen is carried to another flower. This process promotes genetic diversity and can be facilitated by:
• Wind: Pollen is transported by wind from one flower to another place.
• Insects: Flowers are pollinated by bees, butterflies and other insects which visit them in search of the nectar.
• Animals: Flowers are pollinated by birds, bats and other animals which have a taste for pollen and nectar.
• Water: In some of the flora found in water, pollen is transported by water.

3. Fertilization:

Bearing in mind that pollination is the process through which transfer of male germ cells takes place, fertilization takes place on the female reproductive organ after pollination. Once a pollen grain is in the stigma it begins to develop a pollen tube through which pollen travels down the style to the ovary. The male gametes (sperm cells) pass through this tube to get to the ovule.Sperm cells are produced in an organism whose genotype is a dominant allele of the individual producing the sperm cells and an absent allele of the individual producing the germ cells.

In the ovule the sperm cell penetrates the egg cell. This fusion results to the formation of a zygote which is the first cell of a new plant.

Some plants undergo a process called double fertilization, where one sperm cell fertilizes the egg cell, the other sperm cell penetrates into two other nuclei in ovule and forms a triploid endosperm cell, which later develops into the endosperm, a food supply for the developing embryo.

4. Productions of Seed and Fruit:

During fertilization the fertilized ovum forms the embryo within the ovule. The ovule becomes a seed and the ovary part turns into fruit.

• Seed: In seed there is the embryo which is the young plant, food reserves, (endosperm or cotyledon part), seed coat.
• Fruit: The fruit is the mature ovary that encloses and preserves structures of forming seeds. Basically there are a number of objectives that are accomplished by the fruit, and one of this s is to assist in the germination of the seeds through animals, water or the wind.

5. Seed Dispersal:

When the fruit ripens the seeds are ready to be transported from the initial plant. This can happen through various mechanisms:

• Wind Dispersal: Dandelion seeds, for example, are light seeds and can hence be transported by the wind.
• Animal Dispersal: Some seeds are consumed by animals and after some time maybe dropped elsewhere. Others attach to animal fur.
• Water Dispersal: Some seeds of some plants have the ability to float on water for instance coconut seeds can float on water move to other areas.

6. Germination:

During germination, this seed is favored by appropriate conditions. This include the fact that for an embryo, it will develop into the growth of a new plant. The key stages of germination include:

• Imbibition: The seed laughs, it takes in water causing it to expand and crack the seed coat.
• Activation of Metabolism: Water promotes synthesis of enzymes which begins the process of releasing stored nutrient in the seed for use during the growing process.
• Growth of the Embryo: The first organ that forms is the root or radicle and then the shoot or plumule that will transform to the stem and leaves of the mature embryo.

Summary of Sexual Reproduction in Plants:

• Pollination: The process of pollen from male part of flower brings upon the female part.
• Fertilization: The combine of the male gametes with the female gametes to from a zygote.
• Seed Development: Formation of seeds within the ovary.
• Fruit Development: This part of the plant becomes a fruit in order to nurture and to spread seeds.
• Seed Dispersal: Processes through which seeds are transported from the parent plant.
• Germination: This forms the basis to develop into a new plant when in favorable conditions.

One of the main forms of plant sexual reproduction is not only aimed at reproduction of species but also at development of new generations with higher genetic variability, which is crucial for the existence of species in conditions of changes in the environment and diseases.

                           Figure: Structure of Flower