Reproduction in Flowering Plants

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Reproduction in Flowering Plants

Sporogeesis, Gametogenesis and Fertilization:

It is in herent property of the living organisms to continue their race by mechanism of reproduction. The reproduction is a process by which the living beings propagate or duplicate their own kinds. There are three methods of reproduction.

1) Vegetative reproduction
2) Asexual reproduction and
3) Sexual reproduction

1) Vegetative Reproduction:

The reproduction takes place through vegetative parts such as bulbils, corms, rhizome, bulbs, stem cutting, root cutting, etc.

2) Asexual Reproduction:

In asexual reproduction, special cells or asexual reproduction units are produced by the parent body which grow themselves into new individuals. Therefore, the development of new individuals without fusion of male and female gametes is known as asexual reproduction. The asexual reproduction usually includes mitotic division of the body (somatic) cells, it is therefore, also known as somatogenetic or blastogenic reproduction. The asexual reproduction is common only in lower plants and animals and may be of fission, budding, gemmule formation and regeneration types.

3) Sexual Reproduction:

In sexual reproduction development of new individual take place by the fusion of sex called male and female gametes. It is the most common type of reproduction among plants and animals. There are two types of sexual reproduction.

i) Isogamy
ii) Heterogamy

i) Isogamy:

Union of two similar gametes which cannot be distinguished into male and female gametes is called Isogamy. Fusion of such gametes is called conjugation. It is observed in lower plants like mucor and spirogyra.

ii) Heterogamy:

Union of two dissimilar gametes i.e male and female gametes is known as fertilization and the zygote is called Oospores. This type of reproduction is common in flowering plants. And can be divided into A) Apomixis B) Amphimixis

A) Apomixis:

It is an abnormal sexual reproduction in which embryo develops from the egg cell, without fertilization and with or without meiosis. It is of various types- a) Parthenogenesis b) Apogamy c) Apospory

a) Parthenogenesis:

In this case embryo develops directly from the egg cell or male gamete without fertilization. It gives haploid plants.

b) Apogamy:

In this case embryo develops directly from haploid muclei other than egg cells i.e it develops from synergids or antipodal cells of the new embryo sac.

c) Apospory:

In this case embryo develops directly from the somatic cell i.e. it develops from integuments of nucleus.

B) Amphimixis:

This is normal sexual reproduction in which embryo develops from the union of male and female gametes in plants and sperm and egg or ovum in animals.

The process of male gamete formation is known as microsporogenesis and female gamete formation as megasporogenesis in plants.

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