Seeds: Types, Parts and Dispersal

Types of Seeds, Its Parts and Dispersal for Class 5 Science

Through this concept, the students will learn about different types of seeds and the parts of a seed.

After reading the concept, students will be able to:

• Explain what is cotyledon,
• Distinguish between monocots and dicots.
• Enlist monocot and dicot examples.
• Explain the function of seeds.
• Understand what is seed germination.
• Name the agents of seed dispersal.
• Classify seed dispersal by wind and water.
• Analyse between seed dispersal by animals and explosion.

 

Each concept is explained to class 5 students using descriptions, illustrations, and concept maps. After you go through a concept, assess your learning by solving the two printable worksheets given at the end of the page.

Download the worksheets and check your answers with the worksheet solutions for the concept of Types of Seeds, Its Parts and Dispersion provided in PDF format.

 

Parts of a Seed:

The different parts of a seed are discussed below—

• Seed coat: It is the outermost protective covering of the seed. The seed coat protects the tiny baby plant inside.
• Hilum: The hilum can be identified by the scar present on the seed. It is the point where the seed is attached to the flower's ovary.
• Micropyle: The tiny opening on the seed from where air and water enter the seed.
• Radicle: The part of the seed that develops into the new plant's root system.
• Plumule: The part of the seed that develops into the new plant's shoot system.
• Cotyledon: The storehouse of seed nourishes the developing baby plant until the root system is established.

 

Functions of a Seed:

• They ensure the continuity of plant species.
• They protect the embryo (baby plant) inside from external harsh environmental conditions.
• They undergo dormancy under unfavourable conditions.
• They ensure the supply of food till the baby plant is mature enough to grow and synthesise food.

 

Germination of a Seed:

• Seeds germinate in the presence of suitable conditions.
• On absorbing adequate water, the seed swells up, leading to the seed coat's bursting.
• It gives rise to a baby plant called seedling.
• The embryo receives nourishment from the cotyledon till the root system is developed.
• The radicle grows into the root system.
• The plumule is phototrophic and grows into the shoot system.

 

Conditions Necessary for the Germination of Seeds:

• Water: Seeds need a considerable amount of water to swell and open up as most seeds are dry. Water performs the following vital functions—
1. Softens the seed coat and increases its permeability.
2. Provides dissolved oxygen to the embryo inside.
3. Converts insoluble food materials into soluble food materials that the embryo can utilise.
• Oxygen: It is a vital source of energy for the growing embryo. It depends on the oxygen available in the surrounding until and unless it grows enough to produce it by photosynthesis.

 

• Temperature: The seed requires an optimum temperature of around 25- 30°C for germination. The range of temperature varies from seed to seed.

 

• Sunlight: Seeds cannot germinate in the absence of the sun. Hence, sunlight is essential for seeds

 

All cereals are monocots.
Examples: Rice, Wheat, Maize.

All pulses and dicots.
Examples: Moong, Gram, Rajma.

Dispersal of Seeds:

• Dispersal stands for the scattering of seeds to far-off places.
• It is necessary so that the plant species grow in various places.
• The absence of dispersal may lead to the following situations—
1. The plant species would be limited to certain areas only.
2. The new plants will grow only near the mother plant, which would lead to overcrowding and competition for food, light, and space.

 

Seeds Dispersed by Wind:

 

Seeds Dispersed by Water:

 

Seeds Dispersed by Animals:

• Birds and animals eat fleshy fruits and disperse the seeds to faraway places through their droppings.
  Examples:Watermelon, Lichi, Guava, and Mango.
• Some seeds have hooks on their outer surface, which allow them to stick to the animal fur, and in this way, they are carried to different places.

                   Examples: Cocklebur, Beggar tick.

 

Seeds Dispersed by Explosion:

 

New Words

 

Did You Know?

• The seeds of orchids are as fine as dust.
• Dandelion seeds land on the ground like a parachute.
• Ants take the fruit to their colonies and discard the seeds in fertile areas after eating the fleshy part.
• Some fruit-eating fish like Pacus consume fallen fruits and disperse the seeds to flooded areas.
• Alsomitra macrocarpa is the world’s largest gliding seed, with a wingspan of 5.5 inches.