8. Reproduction in Plants

Seed Formation:

This is the third step in the process of sexual reproduction in plants.

Process:

1. After fertilization, the zygote or the fertilized egg grows into an embryo.
2. As the embryo grows, the ovary develops into a fruit.
3. The ovule develops into a seed.
4. Thus, the seed contains an embryo enclose in a protective seed coat.
5. The fruit is the ripened ovary.
6. Some fruits like mango, orange, tomatoes etc. are fleshy & juicy.
7. Some fruits like almonds, walnuts, are hard. 

To remember:

• Ovary is ripened fruit.
• Ovules develop into seeds.
• Zygote grows into embryo.

Seed Dispersal

Definition:

It is the process by which seeds are spread to different places away from the parent plant.

Benefits of seed dispersal:

1. It avoids overcrowding of young plans around their parents plants.
2. It helps in preventing competition between the plant & its own seedlings for sunlight, water & minerals.
3. It enables the plant to grow in new habitats for wider distribution.
4. It provides better chance of survival.
5. It allows colonization of new areas.

Seeds are dispersed by various agents.

To remember:

• Seed dispersal reduces competition.
• It helps plants to explore new habitats.

Methods of seed dispersal

Seed dispersal takes place through following ways:

1. Wind:

• Seeds dispersed by wind are smaller in size & lightweight.
• They have wings or hair like structure.
• These seeds get blown off far away by the wind.

Examples:

2. Water:

• The fruits or seeds of aquatic plant or plants that live near water develop the ability to float.
• Hence they can be carried away with water.
• They usually have a spongy or fibrous outer coat like coconut.

3. Animals:

• Animals & birds disperse seeds in many ways.
• They eat fruits & excrete the seeds away from the parent plant.
• Some seeds have spines or hooks which get attached to the animals body or fur.
• These seeds get carried to distance places with the animal.
• Animals like squirrels collect & bury seeds, some of which may germinate.

Examples: xanthium, urena

4. Explosion:

• Some seeds are dispersed when the fruits burst with sudden jerks.
• This explosion scatters seeds far from the parent plant.

Examples: pea, castor, balsam, etc.

To remember:

• Seeds disperse by wind, water, animals, birds or by explosion.
• After dispersal of seeds, seeds germinate to form new plant.