Embryonic Adaptations & Seed Germination

Understanding Seed Germination

Seed germination is the process by which a seed develops into a new plant. This process involves several stages and adaptations that ensure the survival and growth of the plant. Let's explore the different types of germination and the adaptations involved.

Types of Germination

• Epigeal Germination: In this type, the cotyledons (seed leaves) are pushed above the ground. The hypocotyl (part of the stem below the cotyledons) elongates, lifting the cotyledons.
• Hypogeal Germination: Here, the cotyledons remain below the ground. The epicotyl (part of the stem above the cotyledons) elongates, pushing the plumule (young shoot) above the soil.

Stages of Seed Germination

1. Imbibition: The seed absorbs water, swelling and breaking the seed coat.
2. Respiration: The seed increases its metabolic activity, using stored food to grow.
3. Growth: The radicle (young root) emerges, followed by the shoot.

Adaptive Features of Seeds

• Seed Coat: Protects the embryo from damage and desiccation.
• Endosperm: Provides nutrients to the developing embryo.
• Dormancy: Allows seeds to survive unfavorable conditions.

Examples of Germination

Epigeal Germination: Beans and sunflowers exhibit epigeal germination, where the cotyledons are visible above the soil.

Hypogeal Germination: Peas and maize show hypogeal germination, with cotyledons remaining underground.