In flowering plants, the organ of reproduction is the flower. A typical flower has four different parts sepals, petals, stamens and carpel. Plants carry out sexual reproduction with the help of flowers. The fruit which develops after fertilisation bear seeds that germinate and start the next generation. The plants of the next generation always show genetic variations. Such plants are better adapted to the changing environment. These organs are just as crucial to plants as humans for survival.
Flowers
A flower is a distinctive feature of all flowering plants, and it is an outgrowth of the reproductive stalk. Flowers are visually appealing and come in various sizes, shapes and colours. Colourful flowers attract pollinators that aid in pollen transmission. Sometimes the flowers are colourless but produce fragrances to attract the pollinators.
Flowers pollinated by wind are generally colourless and fragrance less as these need not to
attract pollinators.
The stalk of the inflorescence is called the peduncle. It may be branched or unbranched. Peduncle bears many small modified leaves called bracts. Flowers arise in the axils of bracts. The arrangement of flowers on the peduncle is called anthotaxy. Flowers may be described as bracteate or ebracteate depending upon the presence or absence of bracts. The part from where flowers arise is called a bract. The flower is short or long on a flower stalk which is called a pedicel. The upper part of the pedicel is swollen, spherical-shaped or conical which is called thalamus/Receptacle. Floral leaves are present on it.
Parts of Flowers:
The flower has four parts arranged in whorls. These are
- Sepals- Generally green in colour and protect the flowers till they are in buds.
- Petals- These are either colourful or colourless and nectaries may be present at their base. Their main function is to attract insects, birds, etc. for pollination.
- Stamen -It is the male portion of the flower and is made up of:
- Anthers – pollen-producing organs.Pollen is the male gametophyte of a flowering plant that produces two male gametes on germination.
- Filament- It is the stalk that holds the anthers in place (makes the anther accessible to pollinators). It may vary in length in different flowers.
- Pistil – It is the female portion of the flower and is made up of:
- Stigma- The sticky, receptive tip of the pistil that catches pollen and helps in pollen germination.
- Style- The tube-shaped link between the stigma and the ovary is known as the style which elevates the stigma to help catch pollen.
- Ovary-The basal part of the pistil contains one or many ovules. The ovary forms fruit and ovules inside the ovary form seeds after the process of fertilisation. That’s why in angiosperms seeds are covered by the fruits.
Development of flower:
- Flower development is very standardised since it is under substantial genetic control. It is broken down into several stages, including floral induction, floral meristem creation and flower organ development. A gene regulatory network made up of connecting genes and its protein products are responsible for precise control of the many stages of flower development.
- Flowering-time genes, triggered by developmental signals and environmental factors like plant age, day length and temperature are near the top of the floral Gene Regulatory Network hierarchy.
- Flowering-time genes activate meristem identity genes, mediating the transition from vegetative and reproductive development.
- Upstream regulators of floral organ identity genes and meristem identity genes transform the vegetative meristem to floral meristems.
Post Fertilisation Events in Flowering Plants
Fertilisation is defined as the fusion of female and male gametes to form a diploid zygote. After fertilisation, a series of events occur in the zygote, resulting in a seed. Let’s look at the post fertilisation events in the flowering plant’s process, endosperm, and embryonic formation.
Post-fertilisation is a series of events that occur after fertilisation to develop a seed from an egg and a placenta from the ovary.
There are four post-fertilisation events in angiosperms flower:
- Development of endosperm
- Embryogenesis
- Seed
- Fruit
Conclusion :
Flowers are essential for the reproduction of plants. The various floral parts are peduncles, receptacles, sepals, petals, stamens and pistils. Flowers are living things that are critical to our survival on this planet. They supply food for people and other animals and allow us to breathe by turning carbon dioxide from our exhaled air into oxygen. There are over 80,000 edible flower species on the planet. So sexual reproduction shown by the Flowers is the key to the development of better-suited plant species. Hence, flowers become one of the essential parts of the plants. Flowers of the plants develop into fruit after fertilisation thereby ensuring genetic variation too.