Reproduction in Plants

 

Reproduction in Plants

Plants reproduce by both asexual and sexual methods. Vegetative propagation is a type of asexual reproduction in plants. Let’s learn now about sexual reproduction in plants.

Sexual Reproduction in Flowering Plants

• Sexual reproduction in plants happens through flowers.
• Essential whorls of the flowers such as androecium and gynoecium help in the sexual reproduction of plants.

Non-Essential Parts of Flowers

• The typical structure of flowers contains essential whorls and non-essential whorls.
• Sepals and Petals are called non-essential whorls as they do not directly take part in reproduction.
• Sepals protect the inner delicate whorl during bud condition and also perform photosynthesis if they are green in colour.
• Petals, when they are coloured, attract insects for pollination.

Essential Whorls of Flowers

• Androecium and gynoecium are called essential/reproductive whorls of a flower.
• Androecium produces pollen grains containing male gametes, and gynoecium produces ovules which are female gametes.
• Bisexual flowers contain both whorls, while unisexual flowers contain either of them.
• Each individual member of androecium is called a stamen and consists of an anther and filament.
• Anther produces haploid pollen grains.
• Each individual member of the gynoecium is called a pistil and consists of a stigma, style and ovary.
  

Pollination

The process of transfer of pollen grains from anthers to the stigma of a flower is known as pollination.

• It is required for fertilization.
• Pollination has two types, self-pollination (autogamy) and cross-pollination (allogamy).
• In self-pollination, the transfer of pollen grains takes place from anthers to the stigma of the same flower or another flower of the same plant.
• In cross-pollination, pollens are transferred from anthers to the stigma of another flower.
• Many pollinating agents play their roles in cross-pollination. Examples: water, wind, insects, birds, bats, etc.

Fertilization

Fusion of male and female gametes is known as fertilization.

• In flowering plants, after pollination, the pollens germinate on the stigma surface of the pistil and generate two male nuclei.
• Ovule has an egg cell and two polar nuclei.
• One male nucleus fuses with two polar nuclei and forms a triploid endosperm.
• Another male nucleus fuses with the egg cell and forms the zygote that gives rise to the embryo and future plant.
• After fertilization, the ovary becomes the fruit, and the ovules turn into seeds. All other parts wither away.