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The Flower: I mean, who doesn’t like flowers? Do the flowers bloom solely to please us? Because of its lovely beauty and aroma, the blossom is the most appealing part of the plant. But it’s not just the flowers’ beauty that makes them unique. Plants’ reproductive components are flowers. Many insects and even some mammals eat them, and people use them for various purposes.
They help in reproduction, but they also provide nourishment for other living things. They produce a lot of nectar. There are complete or incomplete flowers in nature. The sepals, petals, stamens, and pistils make up a complete flower. On the other hand, an incomplete flower lacks one or more of these structures. A whole flower has two distinct parts: The Vegetative Part and Part of Reproduction. We’ve covered everything there is to know about reproduction in flowering plants in this post.
A flower can be defined as a specialised structure found in flowering plants that bears reproductive organs and takes part in the process of reproduction. It is involved in the formation of fruits and seeds. Angiosperms are also known as flowering plants. Angiosperms reproduce by sexual reproduction, and flowers are the reproductive parts of these plants.
Flowers may either bear stamen (makes male gametes) or carpel (makes female gametes) or both of these. Thus, it can be said that flowers are the main reproductive parts of the plant.
Each flower is supported by a stalk called a pedicle. This stalk leads to a broad basal region of the flower. This part is called the thalamus. Thalamus holds all four whorls of the flower. There are four important parts to a flower. These parts are arranged in rings called whorls. Four whorls of the flower are:
1. Sepals (Calyx): These are small leaf-like green structures that form the outer whorl of the flower. They act as a supporting system to the floral part. Sepal can be located at the base near the stalk.
2. Petals (Corolla): These are flat, colourful, generally large parts that form the second whorl inside the sepals. Petals usually have a great aroma or fragrance which attracts insects or other vectors for pollination.
Sepals and petals are the non-essential floral organs. Stamen and carpels are essential floral organs as they take part in sexual reproduction.
3. Androecium: Stamens are the male reproductive organs in plants that collectively form the androecium. These are present inside the petals and form the third whorl. Stamens have two parts, the slender stalk called a filament, and anther is the fertile part present at the tip of the filament. These parts are connected by a sterile band called a connective.
The anther has four pollen sacs in each of its lobes. Many haploid pollen grains develop in these pollen sacs through the mitotic division of diploid microspore mother cells. Once these pollen grains are fully matured, they contain two cells: generative cell and tube cell. Later after pollination, the generative cell divides and gives rise to the male gametes within the pollen tube.
4. Gynoecium: Carpel (also known as Pistil) is the female reproductive part in plants and collectively forms the gynoecium. These are the fourth and the innermost whorl of a flower. Based on the number of carpels, flowers are classified into three types, namely monocarpellary, bicarpellary and polycarpellary. Carpel has basically 3 parts:
a) Stigma: Stigma is the uppermost sticky receptive part of the carpel that is exposed to the external environment to receive pollen grains from the anther of a stamen.
b) Style: It is the stalk that connects Stigma with the ovary.
c) Ovary: It is the swollen structure of the carpel that has parenchymatous cushions called placenta in its chambers.
Ovules are attached to the placenta and contain the female gametes or female sex cells of the plant. There is usually more than one ovule in the ovary.
Ovule has one or two layers of covering called integuments with a terminal pore called the micropyle. Each ovule contains only one female gamete of the plant, the one present inside the ovule is called the ovum or egg.
During pollination, pollen grains fall on the stigma of the flower and start to germinate. This process is followed by fertilisation which results in the development of the ovary into fruits and ovules into seeds.
A typical structure of the flower includes four whorls calyx, corolla, androecium and gynoecium. Depending on the presence or absence of one or more floral whorls, flowers are classified into two different types:
a) Complete Flower: A flower that has all four whorls is called a complete flower.
Examples: mustard, Hibiscus, etc.
b) Incomplete Flower: When one or more of these whorls are missing in flower, it is called an incomplete flower. Examples: papaya, watermelon, etc.
Depending on the presence or absence of the male and female reproductive parts, flowers can be classified as:
1. Bisexual: A flower that bears both stamen and pistil is called a bisexual or perfect flower.
2. Unisexual: A flower that lacks one of the (male or female) reproductive structures is called a unisexual flower.
This can be of two types:
a) Female Flower: A flower that lacks stamens is said to female flower or pistillate flower.
b) Male Flower: A flower that does not possess pistil is called a male flower or staminate flower.
The main function of the flower is to carry out the process of sexual reproduction. But, different parts of the flower also carry out many other important functions. Continue reading to know more about the functions of each part of the flower.
|Parts of the Plant||Functions|
|Sepals||Provide protection to flowers during the bud stage.|
|Petals||Brightly coloured and have a strong fragrance to attract pollinators.|
Wind pollinated petals are comparatively dull and without smell and nectar as they do not need insects for pollination.
|Anther||Produce male gametes for sexual reproduction.|
|Ovary||Produce female gametes for sexual reproduction.|
|Nectary||Secretes sweet fluid to attract insects like bees for pollination.|
|Stigma||Receives pollen grains during pollination due to their sticky nature.|
|Style||Pollen tube travels through the style to reach the ovule.|
Flowers are responsible for sexual reproduction in plants. It involves the fusion of male gametes produced in anther with the female gamete produced in the ovary of the flower. This results in the formation of a diploid cell called a zygote. The zygote undergoes a series of divisions and stages to form an embryo that later develops into new plants.
This process takes place in 2 steps
Let’s see these two processes in detail:
1. Pollination: Pollination can be defined as the transfer of pollen grains from the anther to the stigma. The pollen grains from another must be carried to the stigma for the fusion of both gametes. Pollination occurs in various ways and can be of two types:
a) Self Pollination: When pollen grains from the anther are transferred to the stigma of the same flower or another flower on the same plant, then it is called self-pollination.
b) Cross-Pollination: When pollen grains from the anther of a flower on one plant are transferred to the stigma of a flower on another similar plant, it is called cross-pollination. Cross-pollination is usually carried out by insects. When an insect visits a flower for sucking nectar, pollen grains stick to its body parts. When that insect sits on another flower, the pollen grain is transferred to the stigma of that flower of a similar kind. Blowing wind also takes part in transferring pollen grains from one flower to another for cross-pollination.
2. Fertilisation: Fertilisation is the fusion of male and female gametes in the flowers of the plant. Once pollen grains reach the stigma, they start to germinate and develop a pollen tube that passes through the style of the carpel. Once the pollen tube reaches the ovary, it enters an ovule through its micropyle. It carries two male gametes and a tube nucleus. When the pollen tube reaches the embryo sac, it bursts open to release male gametes, which fuse with the egg or ovum to form a diploid zygote.
If the second male gamete fuses with the central cell to form triploid primary endosperm, this process is called triple fusion as it includes the fusion of three nuclei. As the process of fusion or fertilisation takes place two times, it is called double fertilisation. The primary endosperm cell produces a tissue called endosperm that is used by the embryo to obtain nourishment. Endosperm gets nourishment from the nucellus and the plant. It is very important for the development of an embryo in further stages. The fertilised ovule develops into a seed, and the ovary develops into a fruit. The seed contains a baby plant, also called an embryo and reserved food required for its growth in future.
Flowers are of great significance due to the following reasons:
1. Flowers of some plants such as cauliflower, broccoli, and cabbage., are edible and eaten by many animals.
2. Ovary of the flower develops into fruits that is food for a large population of animals.
3. Some flowers like Hibiscus, lavender, chamomile, etc., have medicinal properties and are used in the preparation of ayurvedic medicines.
4. Many flowers, such as rose, and lavender are used to make beauty products that are sold commercially.
5. Flowers with strong scents are used in perfumes.
6. They are also used for decorative purposes.
There is always something special about plants and their parts that astonish us. Below are some interesting facts about flowers that may surprise you. Continue reading to find out.
1. Roses are called the ‘queen of the garden’ as they are the prettiest flowers among all.
2. Rafflesia arnoldii is a rare and the biggest flower in the world, usually found in the rainforest of Indonesia.
3. There is a rare flower named Neelakurinji that blooms once in \(12\) years and is found in India.
4. Similarly, there is a plant known as the century plant or Agave americana as its flower blooms once in \(100\) years.
5. The Middlemist’s Red Camellia is the rarest flower as there are only two known examples that are believed to exist in all over the world.
Bees make honey from the nectar of flowers. These insects get their food from flowers. Flowers also enhance natural beauty. Oil is also extracted from the flowers. Many herbs and medicines are also made from flowers.
There is also a religious tradition of offering flowers to deities. Offering flowers at the feet of the Lord is considered reverence. The deities are also garlanded with flowers. It has been a tradition to garland flowers to pay respect to any respectable person.
Flowers help in plant reproduction. Reproduction occurs by the pollination method. Humans also take flowers as food. Many species of flowers are suitable for food.
1. Rafflesia: Found mainly in Malaysia and Indonesia, Rafflesia is an astonishing parasitic plant, whose flowers are about 1 meter in diameter, the largest of all plants in the plant world and can weigh up to 10 kilograms. Its smallest species have been found to be 20 cm in diameter. In all species, the skin of the flower appears fleshy to the touch and the flower smells of rotten flesh, which attracts certain insect moths.
It takes 9 to 21 months for Rafflesia to bloom in full bloom but its life span is only five to seven days.
2. Black Bat Flower: It is full black in colour and its texture is like glitter. The petals of this flower look like a moustache and it is up to 28 inches long. Seeing its strange colour form, it is also called the devil flower in many places. This flower is also found blooming in green, purple, brown, and red colors. It requires good soil and plenty of water to thrive. It is mainly found in Africa, South America, Thailand, Malaysia and China.
3. Wolffia: Wolffia is the smallest flower in the world. It is so tiny that it can only be seen under a microscope. Its plant is found in water. The weight of one flower is equal to two particles of salt. They do not have any roots, branches or leaves and are found in calm and clean ponds. The world’s smallest fruit, Utrikal, is produced from each of its flowers.
4. Belladonna: It is considered to be the world’s most dangerous flower, its roots, leaves, flowers and fruits are all toxic and deadly, in which a substance called entropion is found, which makes it poisonous. The scientific name of this flower, Atropa, was inspired by the Greek goddess Atroposaur, the goddess of death. Also, Belladonna is called a beautiful woman in the Italian language. This bell-shaped flower is two centimetres long of purple colour.
The flowers are the parts of the plant responsible for the development of fruits and seeds. Initially, we see a bud that blooms to form a beautiful flower, mostly with bright colours and attractive smells. These flowers, after pollination and fertilisation, are changed into tasty fruits that we eat. Thus, flowers are of great importance both before and after changing into fruit.
Q.1. What is a flower?
Ans: A flower can be defined as a specialised structure found in flowering plants that bears reproductive organs. It is involved in the formation of fruits and seeds.
Q.2. What is the major function of a Flower?
Ans: The main function of the flower is to facilitate sexual reproduction in the plant by producing male and female gametes.
Q.3. What’s the middle part of the flower called?
Ans: The female reproductive part, which is called the pistil or carpel is present in the middle part of the flower. The pistil has basically three parts, stigma, style, and ovary.
Q.4. Explain the flower with an example.
Ans: We can see the four main parts of the flower, sepal, petals, stamen, and pistil, along with the pedicle and receptacle in the diagram. Stamen has two main parts another and the filament. Carpel or pistol is the female sex organ that can be differentiated into stigma, style, and ovary. Anther produces pollen grains (male gametes), and the ovary produces ovules (female gametes).
Q.5. What are the 4 main parts of the flower?
Ans: A typical structure of the flower includes four main parts that are calyx, corolla, androecium (stamen), and gynoecium (carpel or pistil).
Q.6. What’s the female part of the flower known as?
Ans: The female part of the flower is known as the pistil or carpel.
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