Sexual Reproduction in Flowering Plants: Germination of Seeds
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Germination of Seeds
The seed germination begins the moment seed absorbs water, swells, and bursts through the seed coat.
When the seeds are obtained from a plant, they are in dry and dormant state.
These seeds begin to grow as soon as they get water, air, soil, etc.
In simple germination can be defined as the beginning of the growth of a seed.
The enzymes function in the seed with the help of water.
The enzymes perform a function of digesting stored food thereby making it soluble.
Seed Germination
Functions of a Flower
The main function is the reproduction of individual species.
They also help in development of pollen tube, formation of gametes and fertilization.
The large and colored petal helps in attracting insects.
The filaments support the anther.
Angiosperms of the flowers help in diverse modes of pollination.
Flowers are also used as tokens of love or esteem.
Brightening decorations at home.
For worship purpose.
Megasporangia and Megasporogenesis
Megasporangia is also known as female sporangia.
It produces megasporocytes (megameiocytes) that yield megaspores.
The sporangia may be borne in:
Specialized structures such as sori in ferns.
Cones (strobili) in some pteridophytes.
Most gymnosperms
Flowers in angiosperms
Plant Ovules with Megasporocytes
Inflorescence
The collective cluster of flowers is termed an inflorescence in those species that have more than one flower on an axis.
Most members of the very large composite (Asteraceae) group is the common example.
It may include specialized stems and modified leaves known as bracts.
A single daisy or sunflower, for example, is not a flower but a flower head.
Floral Diagrams and Floral Formulae
Floral diagrams are used to represent the structure of a flower.
The diagrams may show important features of flowers, including the relative positions of the various organs.
A way to represent the structure of a flower using specific letters, numbers, and symbols is known as floral formula.
Self-Pollination
The pollen from the anther is deposited on the stigma of the same flower or another flower on the same plant.
Cross-Pollination
The transfer of pollen from the anther of one flower to the stigma of another flower.
Cross-pollination occurs on a different individual of the same species.
Cross-Pollination
FAQs
Q 1. What are the various important parts of a flower?
Answer:
The various important parts of a flower are:
i) Receptacle
ii) Sepals
iii) Petals
iv) Stamen
v) Carpel
Q 2. What are the three agents of Pollination?
Answer:
Three agents of Pollination are:
i) Anemophily, which occurs due to the impact of wind.
ii) Hydrophily, which occurs due to the impact of water.
iii) Zoophily, which occurs due to the impact of creatures.
Q 3. What is Double Fertilization?
Answer:
The process of fertilization occurring in angiosperms is called Double fertilization.
Here one vegetative and two generative cells form into a male gamete with the development of pollen grains.
Q 4. What is the difference between Self-pollination and Cross-pollination?
Answer: Self-pollination takes place when the pollen from the anther is deposited on the stigma of the same flower, or another flower on the same plant.
Cross-pollination occurs when there is a transfer of pollen from the anther of one flower to the stigma of another flower on a different individual of the same species.