Theory:

Flowers are the colourful and beautiful part of the plant that are of various shapes, sizes, and colours. They are the reproductive part of the plant.
 
Important!
Not all of the flowers are colourful (brightly coloured).
Different parts of a flower include:
  1. Petals
  2. Sepals
  3. Stamens
  4. Pistil
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Petals
  • Prominent and the colourful part of a flower that attracts insects like bees, butterflies, and small birds.
  • The number and colour of petals vary in nature. There is a unique fragrance to each of the flower which attracts the insects.
  • The layer of petals is known as corolla.
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Sepals
  • The small leafy part present under the petals which protects the flower when it is a bud.
  • They can be joint together or separate.
  • The outermost layer of the flower is also known as calyx.
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Example:
Some examples of flowers having joined sepals - Hibiscus, Datura, Mustard, tomato. Some examples of flowers having separate sepals - Lotus, Jasmine, Rose, Mustard.
Stamens
  • Stamens are the male part of a flower which consists - anthers (top of the stamen) and filament (stalk of filament).
  • Anther contains pollen grain which are enclosed in it.
  • The stamens surround the pistil (female part).
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Pistil or Carpel
  • The pistil is the female reproductive part of a flower (innermost part of a flower).
  • It consists of stigma, style, and ovary.
  • Stigma is the top part of a pistil, followed by the style (middle part) which connects the stigma to the ovary (base part of the flower).
  • Ovary is the swollen (lowest) part of the pistil.
  • Ovary encases ovules (one or many) that are egg-like structures. Ovules contains the female sex cells and develops into a seed after fertilization.
Important!
The ovary develops into the fruit.
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The number of petals, sepals, stamens and pistils can be different in different flowers. Some of the parts may even be absent in some instances.
Important!
In most of the plants, the stamen and pistil are present on the same flower, while in some plants there are separate flowers that contain the male and female parts of the plant.
Reference:
https://www.shutterstock.com/image-vector/structure-stamen-carpel-flower-part-diagram-1318599074