A flower, very often referred to as a blossom, it is the reproductive structure observed in flowering plant life(plants of the division Angiospermae). The biological characteristics of a flower is to facilitate reproduction, typically via means of providing a mechanism for the union of sperm with eggs. Flowers might also additionally facilitate outcrossing (fusion of sperm and eggs from distinct individuals in a population) as a result of cross-pollination or permit selfing (fusion of sperm and egg from the same flower) while self-pollination occurs. In addition to facilitating the reproduction of flowering plants, flowers have long been famous and utilized by people to deliver beauty to their environment, and additionally as items of ritual, esotericism, witchcraft, religion, medicine and as a supply of food.
Flowers are of two types:
- Complete Flower: A flower that has all four whorls is known as a complete flower. Example: Hibiscus, etc.
- Incomplete Flower: When one or extra of those whorls are lacking in a flower, it is known as an incomplete flower. Examples: watermelon, etc.
Further depending on the presence or absence of the male and female reproductive parts, flowers can be labelled as:
- Bisexual: A flower that bears both stamen and pistil is known as bisexual flower.
- Unisexual: A flower that lacks one in all (male or female) reproductive structures is known as unisexual flower.
Parts of a flower
The various parts of flowers are as follows:-
Vegetative part
The vegetative components of flower are:
Petals: Those are generally brightly colored to attract insects for pollination. The form and color of petals range substantially in plants.
Sepals: Usually sepals are green, leaf-like and protect the flower during the bud stage. Sepals in a few can be united or can be free.
Reproductive parts of a flower
The reproductive parts of flower are:
Stamen: are male reproductive structures of a flower. These are typically referred to as Androecium.
It has 2 parts:
Anther: it is a swollen, yellowish colored structure. These are normally bilobed and every lobe has two chambers, the pollen-sacs (microsporangia). The pollen grains(microspores) are produced in pollen-sacs. A sterile stamen is referred to as staminode and does no longer contain pollen grains.
Filaments: it is a thin stalk-like structure, it is characterised to preserve the anther.
Pistil: it is the female reproductive portion of flowers. A pistil may also contain one to numerous carpels. Each carpel represents one megasporophyll. A sterile or diminutive pistil is referred to as pistillode.
A pistil comprises three parts-
Stigma: It is the tip and receptive part of the pistil. It gets and nourishes the pollen grains. It is a terminal part of style. It can be elongated, knob- like or barely pointed. In a few flowers, it may be lobed, funnel-shaped, branched or feathery. Surface of stigma can be smooth or rough, hairy or sticky, in lobed condition, the variety of lobes normally corresponds to the number of fused carpel.
Style: it helps in the attachment of stigma to the ovary. It is an elongated structure.
Ovary: it is a large basal part, on which lies the elongated tube, the style.
Types of Ovary on basis of Locus
1. Unilocular: with one locule,
e.g. Pea.
2. Bilocular: with two locules, e.g. Mustard.
3. Trilocular: with three locules,
e.g. Asparagus.
4. Tetralocular: with four locules, e.g., Ocimum.
5. Pentalocular: with five locules, e.g., China Rose.
In the locules or chambers are present oval outgrowths referred to as ovules connected to a flattened cushion-like tissue referred to as placenta. Ovule has one or two layers of envelope known as integuments with a terminal pore known as the micropyle. Every ovule has only one female gamete of the plant, the one present inside the ovule is known as ovum or egg.
At the time of pollination, pollen grains fall on the stigma of the flower and start to germinate. This process is observed with the aid of using fertilisation that results in the development of the ovary into fruits and ovules into seeds.
Whorls
A standard flower includes four floral whorls on the receptacle or thalamus. Those are Calyx, Corolla, Androecium and Gynoecium.
1. Calyx: the first whorl of the flower. It consists of leaf-like green sepals. Sepals enclose the bud and protect the delicate parts within. When all sepals are free, calyx is referred to as polysepalous and while united, it is gamosepalous.
2. Corolla: It is the second one whorl of the flower, and includes some petals. In the majority of flowers, petals are brightly colored, scented and are of diverse shapes. They attract bugs for pollination. If petals are free from one another, the corolla is polypetalous, and if there is any degree of fusion among the petals, it is gamopetalous.
3. Androecium: This is the third whorl of flower and is the male reproductive organ such as stamens. Each stamen is a product of a component: filament, and anther. Since every stamen is considered to be a highly modified leaf, it is termed as microsporophyll.
4. Gynoecium: This is the fourth whorl of flower and is the female reproductive organ of the flower. It is called a pistil. It occupies central position on the receptacle and is composed of ovary, style and stigma and those component parts are referred to as carpels. Depending upon the variety of carpels present, gynoecuim of a flower
Types of Gynoecium
1. Monocarpellary: one carpel, e.g., Pea
2. Bicarpellary: two carpels, e.g., Calotropis.
3. Tricarpellary: three carpels, e.g., .
4. Tetracarpellary: four carpels, e.g., Datura.
5. Pentacarpellary: five carpels, e.g., China Rose.
Functions of flower
The primary feature of the flower is to perform the method of sexual reproduction. But there are few other functions such as:
- Flowers of a few plants such as cauliflower, broccoli, etc. are fit for human consumption and are eaten by many.
- Ovary of the flower develops into fruits that is food for population of animals.
- Many flowers, including rose and lavender are used to make splendor merchandise which are offered commercially.
- Flowers carry the process of pollination, in which the process of transfer of pollen grain from male anther is transferred to the female stigma.
Conclusion
Hence, flowers are the unit of reproduction in plants. Flower’s male reproductive structure known as stamen and female reproductive structure known as pistil. The process of pollination is carried out in flowers. Due to the process of pollination, flowers are able to reproduce and produce fruits or seed sets. Flower is a fascinating organ of angiosperms.