A gram seed (like the seed of a chickpea) has a specific structure that is adapted for germination and growth. The main parts of the gram seed are:
1. Seed Coat (Testa):
- Outer Protective Layer: The seed coat is a tough outer covering that protects the seed from physical damage and water loss. It also provides protection from pathogens.
- Color: The seed coat may vary in color, typically brown or beige.
2. Cotyledons (Seed Leaves):
- Two Cotyledons: The gram seed has two large cotyledons, which are the seed leaves. These cotyledons store nutrients (mainly starch) that will be used by the developing plant during the early stages of germination.
- Role in Germination: The cotyledons are the first structures to emerge from the seed during germination and provide nourishment to the young plant.
3. Embryo:
- Radicle (Root): The radicle is the first part of the embryo to grow and develop into the root system when the seed germinates.
- Plumule (Shoot): The plumule is the part of the embryo that will grow into the shoot of the plant, developing into stems and leaves.
4. Hilum:
- The hilum is a small scar on the seed coat, marking the point where the seed was attached to the parent plant. It is visible as a small indentation.
5. Micropyle:
- The micropyle is a small pore near the hilum. It allows water to enter the seed during the process of germination.
6. Endosperm:
- In some seeds, like the gram seed, there may be a small amount of endosperm, which is the tissue that nourishes the developing embryo. However, in legumes like chickpeas, most of the nourishment is stored in the cotyledons, not the endosperm.
This structure allows the gram seed to protect itself during dormancy and provide all necessary nutrients for the embryo during germination.