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प्रश्न
What is a flower ? Draw a neat labelled diagram showing the L.S. of a typical flower.
उत्तर
A flower is a reproductive part of a plant. It helps in sexual reproduction as it has male parts and female parts. A fully opened flower has the following parts:
Stalk—A flower is attached to the shoot by means of stalk or pedicel stalk. The tip of the stalk is swollen or flattened. This is called torus or thalamus or receptacle.
The different parts of a flower are inserted on the thalamus. There are usually four whorls as
Calyx (Sepals)
Corolla (Petals)
Androecium (stamens)
Gynoecium (Carpels) Present on the thalamus
- Sepals (Calyx): These are the outermost part of the flower. These are leaf like and green in colour. This is the outer covering of the flower and form outer whorl in a flower. The Calyx (sepals) enclose the inner parts of the flower when it is a bud. It is protective in function.
- Corolla (Petals): Petals form the second whorl inner to the sepals. These are usually coloured, gaudy, or white in colour and scented and give sweet smell. The value of a flower is due to the attractive colour of the petals. These attract the insects for pollination.
- Stamens (Androecium): The third whorls inner to the petals are stamens. This third whorl is called Androecium. These are the male parts of the flower. Each stamen is formed of a long narrow, hair like structure called filament. On its tip it bears, a rounded broad sac like structure called anther. Each anther has two anther lobes. Each anther lobe has two pollen sacs which have powdery mass called pollen grains.
- Carpels (Gynoecium): Carpels are the inner most or fourth whorl in a flower. It is lodged on the thalamus and forms the female part of a flower. This whorl of carpels is called gynoecium. Each carpel or pistil has three parts.
(a) The lower most, swollen part is ovary. It is attached to the thalamus.
(b) The middle part is style which is narrow, thread like.
(c) Stigma: The style ends in a knob like, rounded structure which is sticky in nature to receive the pollen grains.
The ovaries contain ovules which later turn into seeds after fertilization and the ovary wall forms the fruit sometimes the thalamus also becomes a part of the fruit as in apple.
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संबंधित प्रश्न
When an insect sits on the flower of a plant then some particles A present in the top of little stalks in the flower attach to its body hair. When this insect now sits on the flower of another similar plant, then particles A attached to the hair of insect are put on the top of a flask-shaped organ at the centre of flower. The particle A grows a long tube b from the top of flask-shaped organ through which C moves down and reaches the bottom part of flask-shaped organ. Here C fuses with the nucleus of d contained in structure E. the fusion of C and D forms a new cell f which grows and develops into a seed of the plant.
(a) What are particles A? What is the process of transferring A from one flower to another flower of similar plant by the insect known as?
(b) What is the name of tube B?
(c) What is C which moves down through the tube B?
(d) Name D and E.
(e) What is F?
State whether the following statement is true (T) or false (F):
Stamens make egg cells.
Answer the following question.
How does suitable pollination lead to fertilization?
What is meant by pollination?
__________ is present in unisexual flower.
What is the structural unit of sexual reproduction in plant?
What are the agents for pollination?
Name the reproductive parts of an angiosperm. Where are these parts located? Explain the structure of its male reproductive part.
Explain the post fertilization changes that occur in the ovary of a flower.
Given below is a diagram of a germinating seed. Label the parts that:
- gives rise to future shoot.
- gives rise to future root system.
- stores food.
