Reproduction in Plants

Like any other living organism, plants also reproduce offspring. The process of reproduction in plants is called pollination. The flowers contain male and female sex parts in them. The male sex part of the flower is called the stamen and the female sex part is called pistils; the anther part of the stamen contains the pollens. Many modes are responsible for sexual reproduction, like wind and water pollination in plants. These pollinations give rise to new plants. Then, the plants grow and give seeds and fruits, which is considered reproduction.

There are two types of reproduction in plants, such as:

1. Sexual method
2. Asexual method

Sexual Reproduction

The fusion of gametes produces new offspring. This process is known as sexual reproduction in plants. Sexual reproduction brings evolution and variations. Even though sexual reproduction occurs, the offspring are not the same as the parental plant.  

PROCESS OF SEXUAL REPRODUCTION

• A flower is the part of the plant where sexual reproduction takes place
• The meiosis phase is a significant phase for sexual reproduction, and the two main processes involved in sexual reproduction are pollination and fertilisation
• After fertilisation, these flowers turn into fruits. 

Reproductive part of the flower

Flowers have reproductive organs. The four parts of a flower are:

1. Calyx/ sepals
2. Corolla/ petals
3. Androecium/ male reproductive organ
4. Gynoecium/female reproductive organ

CALYX – These are small green leaflets that occur at the base of the flower to safeguard the flower during the bud stage. The primary colour of the calyx is green. It is one of the reproductive parts of a flower. 

COROLLA – These are the colourful petals present in flowers. Corolla attracts many insects such as butterflies and bees. It helps in pollination.

STAMEN – The male sex organ of a flower is called the stamen. The pollen is present in the anther which is situated inside the stamen.  Stamen is structured like filament, the sac-like anther stores pollen grains in the plant. Filaments provide support to the anther.

GYNOECIUM – Pistil produces female gametes consisting of an ovary, style, and stigma. The ovary is present in the base of the plant that produces ovules. The style (tube-like structure) connects the stigma and ovary to allow the pollen grains into the ovary. The place that receives pollen grains during pollination is stigma. It is one of the reproductive parts of the plant.

Types of Flowers

The position of stamens and pistils determines whether the flower is bisexual or unisexual. There are two types of flowers:

1. Bisexual flower
2. Unisexual flowers

BISEXUAL FLOWERS – The flower is said to be bisexual if the stamen and pistil are present in the same flower—for example, rose, hibiscus, Gulmohar, mustard.

UNISEXUAL FLOWER – If both the androecium and gynoecium are present in the same flower, then the flower is known as unisexual flowers. 

For example, papaya, maize and cucumber.

Pollination

The reproductive part of a plant is the part where pollination occurs. In this process, pollen grains move from another to stigma. Two types of pollination occur in plants. They are:

• Self- pollination
• Cross-pollination

SELF-POLLINATION

It is the kind of pollination where pollen of the same plant lands on the flower’s stigma. This process is also called autogamy. Here are the two necessary conditions required for autogamy to take place.

• The anther and stigma should be positioned or located at the distance
• Anther-stigma is synchronised when the pollen is released

CROSS-POLLINATION

Pollen from another flower gets transferred to the stigma of another flower of different species. 

AGENTS OF POLLINATION

There are many agents of pollination that are responsible for reproduction in plants. They are:

• Wind
• Water 
• Insects 
• Birds 

WIND POLLINATION

As the pollen grains are light in weight, they can be easily carried away by the wind. As stigma is sticky, it can easily receive pollen. For example 

1. Rice
2. Maize 

WATER POLLINATION

Water pollination is common in aquatic plants. Due to the water current, the pollen is brought to the water and then supplied to the flowers. For example

1. Hydria
2. Coconut

INSECT POLLINATION

 As the flower is brighter in colour and sweet nectar, insects get easily attracted to it. The pollen grains stick in the insect’s wings and legs and get deposited in the flower’s stigma. 

• Hummingbirds and sunbirds are also responsible for the pollination
• Garden lizards (reptiles) help in pollination
• Squirrels (mammals) help in pollination

ASEXUAL REPRODUCTION

Only one parent plant is involved in reproduction in the case of asexual reproduction. 

Different Modes of Asexual Reproduction

• Vegetative propagation
• Budding
• Fragmentation
• Spore formation

REPRODUCTIVE PARTS OF PLANT

Reproduction takes place in parts of the plant that are considered a natural method of vegetative propagation.

1. Root
2. Stem
3. Leaves

MODIFICATION OF STEM

Some modifications of the stem that act like reproduction in plants are Bulb, Tuber, Rhizome, and Runner. 

TYPES OF ASEXUAL REPRODUCTION

There are two types of asexual reproduction. They are:

1. Natural method
2. Artificial method

Natural methods

They are subdivided into:

• Budding
• Vegetative propagation
• Fragmentation
• Spore formation

Artificial methods

They are subdivided into:

• Cutting
• Grafting
• Layering
• Micropropagation

NATURAL METHOD

BUDDING

 If the cell division occurs at a particular site, a bud is formed. For example, if you keep the potato in your home for a long period, you can see the formation of bud on the surface of the potato through naked eyes. 

VEGETATIVE PROPAGATION

The reproduction can take place in any part of the plant.

Root – Roots are modified into the tuber, giving rise to adventitious buds, forming a new plant. For example, sweet potato. 

Stem – At the nodes of the stem, new buds are formed, which develop into new plants.

Leaves – If the leaves get detached from the parent plant, they can become a new plant. For example, Bryophyllum. 

FRAGMENTATION

In this mode of reproduction, the new plant is developed from the parent plant. In this, some part like the stem or root of the parent plant gets fragmented and turn into a new plant. Example- Spirogyra.

SPORE FORMATION

In this method, the spore is formed, covered by a hard structure to withstand environmental conditions such as salinity and humidity. Organisms like fungi reproduce by producing spores that germinate under favourable conditions to form new organisms. For example, bread mould, mushroom, mosses and ferns. 

Conclusion

In conclusion to the topic reproduction in flowering plants, we have learnt about the reproduction in plants, reproductive parts of the plant, reproductive parts of the flower, sexual reproduction, asexual reproduction, budding and fragmentation, etc. We also learned about different factors that are responsible for pollination like wind, water and animals and plants. Natural methods like budding, fragmentation, vegetative propagation and more are also responsible for the reproductions of plants.