The root cap is a protective structure located at the tip of the root in plants. It plays a crucial role in root growth and development. The formation of the root cap is attributed to a specific group of cells known as the calyptrogen.

What is the calyptrogen?
The calyptrogen is a group of cells located at the apical meristem of the root. It is responsible for the formation of the root cap. The calyptrogen is derived from the root apical meristem, which is the region of actively dividing cells at the tip of the root.

Process of root cap formation:
The formation of the root cap involves several stages. Here is a detailed explanation of each step:

1. Cell division: The calyptrogen cells undergo active cell division, leading to the formation of new cells. These new cells are pushed forward, away from the apical meristem, towards the root tip.

2. Differentiation: As the new cells move forward, they undergo differentiation to form specialized cell types that make up the root cap. The differentiated cells include columella cells, lateral root cap cells, and peripheral cells.

3. Columella cells: Columella cells are located at the center of the root cap and are responsible for gravity perception. They contain specialized starch-filled amyloplasts, which help the root in its geotropism response.

4. Lateral root cap cells: Lateral root cap cells surround the columella cells and provide additional protection to the root tip. They are involved in the secretion of mucilage, which lubricates the root as it grows through the soil.

5. Peripheral cells: Peripheral cells are located at the outermost layer of the root cap. They serve as a protective barrier against mechanical damage and help in the absorption of water and nutrients from the soil.

Conclusion:
In conclusion, the root cap is formed by the calyptrogen, a group of cells derived from the root apical meristem. The calyptrogen cells undergo division and differentiation to form specialized cell types, including columella cells, lateral root cap cells, and peripheral cells. These cells collectively make up the root cap, which plays a crucial role in root growth and protection.