Reproduction In Plants

The flower is the reproductive part of a plant. After fertilization, the ovary grows into a fruit, and the seeds develop from the ovules. For some plants, the branch is used for vegetative propagation which is a type of asexual reproduction.

The flower is the reproductive part of a plant. After fertilization, the ovary grows into a fruit, and the seeds develop from the ovules. For some plants, the branch is used for vegetative propagation which is a type of asexual reproduction.

Fragmentation is a type of asexual reproduction, where the organism (e.g., algae) breaks up into smaller pieces or fragments. These fragments grow into mature individuals. Here, this process continues for every new individual formed, and hence they spread rapidly.

The winged structure of seeds of drumstick and maple helps them to travel long distances by wind.

Seeds of drumstick(left) and maple(right)

The ‘eye’ of the potato and the buds in the margin of leaves of Bryophyllum plant can produce new plants by vegetative propagation. Plants produced from vegetative propagation takes less time to grow when compared to the plants produced from seeds.

Eye of the potato(left) and buds of Bryophyllum leaf(right)

The number of ovules found in an ovary is different for different flowers.

In sexual reproduction, new plants are produced from seeds.

Two plants are not always necessary for sexual reproduction. In bisexual flowers, there are cases where pollen lands on the stigma of the same flower (self-pollination), and then fertilization takes place.

Pollination is the process of transfer of pollen grains (which contains male gametes) to the stigma of a flower (the female reproductive part consists of stigma, style, and ovary which contains the female gametes). This process allows the contact between male and female gametes, leading to fertilization. Hence fertilization can only take place after pollination.

Pollination can be caused by different agents such as wind, water, insects etc.

The transfer of pollens from the anther to the stigma of a flower is called pollination.

Spore formation

The method of asexual reproduction found in fungus, moss and fern is spore formation. The parent plant releases spores into the air. These spores are covered by a protective coat to withstand unfavorable conditions. The spores float in the air, and under suitable conditions (like hot and humid area), they fall into certain places and develop into a new individual.

Rice

Sugarcane, potato, and rose can be grown using vegetative propagation (asexual reproduction). Potato can be grown by planting the cut pieces containing an ‘eye’ (looks like scars). Rose can be grown by planting the cut piece of branch (or ‘cutting’). Sugarcane can be grown using stem cutting containing a bud. Rice is grown from seeds (sexual reproduction).

Branch, pollen grains.

Rose flower is a bisexual flower. Rose plant can be grown by vegetative propagation as well as sexual reproduction.

Vegetative Propagation:

A piece of the branch is properly cut from the parent rose plant, and buried in the soil. Watering it regularly will help in its growth.

Additional Info:

Alternatively, there is a method called bud grafting, where the bud of one rose plant is removed and placed on another plant in a particular way. Then these are held firmly using a rubber band. This technique is mostly used to create hybrid plants.

Sexual Reproduction:

Rose plants can also be grown from seeds. In this method, pollination takes place. The pollen grains would be transferred from anther to stigma of the rose flower. After that, fertilization occurs resulting in the formation of seed. The seed can be dispersed by various agents (e.g., insects). Under suitable conditions, the seed will grow into a new plant.

Self-pollination

The picture shows the transfer of pollen from the anther to the stigma of the same flower. This process is called self-pollination, as the process involves only one flower.

Sometimes, plants grow without a human support. New plants are produced from seeds or from vegetative parts. The seeds developed in the parent plant are dispersed to different locations by various agents, like wind, water, animals or insects. When these seeds get sufficient resources, they start to germinate to form new plants.

Moreover, new plants can grow through vegetative propagation also. In the case of Bryophyllum plant, the leaves contain ‘buds’ which can grow into new Bryophyllum plants. These leaves could fall from the parent plant, into the soil. In a suitable environment, the buds develop into new plants.

This explains the presence of many small plants in Paheli’s garden.

(a) – Pollen grain, (b) – Pollen tube, (c) – zygote formation

The diagram shows the fertilization process occurring in plants after pollination takes place. Fertilization is the process of fusion of male and female gametes to form a zygote.

(a) The growth is called a mould. It is formed by fungus.

(b) The growth takes place through spore formation. The parent produces hundreds of spores which are released into the air. The spores have a protective coat that protects them from unfavorable conditions. These are randomly scattered to various places by wind, water etc. Under suitable conditions, the spores would fall into places like moist bread pieces. The spores germinate to form new individuals. This process continues.

(a) Seed dispersed by wind – (i) Maple seed, (ii) seed of madar

(b) Seed dispersed by water – given seeds do not support seed dispersal by water

(c) Seed dispersed by animal – (iii) Xanthium

Seeds of maple and madar have wing-like structure and hence are dispersed by wind.

Xanthium is a spiny seed with hooks which sticks or gets attached to bodies of animals. Hence it is dispersed by animals.

Even though coconut is large and heavy, it contains an outer fibrous coat which has the ability to float on water. It can drift in water bodies to different locations for a long period of time.

Coconut dispersed by water

The thick external husk protects the seed from animals, and unfavourable environmental conditions.

The parts have been labeled in the following figure.

(a) zygote (b) fertilization (c) embryo (d) seeds (e) fruit

The completed diagram of a bisexual flower looks like:

The missing parts have been labeled in the diagram itself.

The parts marked (a), (b), (c) are:

(a) – petal (b) – sepal (c) – filament of stamen

Additional info:

Sepal is a part of flower which protects the flower bud. It also helps in giving support to the petals of the flower.

(a) Seeds with wings are dispersed by wind. Due to the winged structure, the wind can easily blow off these seeds to different locations.
Example: seeds of drumstick, maple

(b) Small and light seeds can be dispersed by wind, or water. The light weight of seeds allows them to float on water, or be carried away by wind.
Example: light seeds of grasses

(c) Seeds with spines/hooks get attached to the bodies of animals. Thus these seeds are dispersed by animals to different places.
Example: Xanthium, Urena