Which one of the following cells types always divides by anticlinal cell division?

Options

A. fusiform initial cells
B. root cap
C. protoderm
D. phellogen

Explanation

To determine which cell type always divides by anticlinal cell division, we need to analyze the options provided:

1. **Fusiform Initial Cells**: These cells are responsible for producing the axial system of the plant, including xylem and phloem. They typically divide periclinally, which means they divide parallel to the surface of the plant, leading to the formation of elongated cells.

2. **Root Cap**: The root cap is made up of meristematic tissues that protect the growing tip of the root. The cells in the root cap do not consistently divide by anticlinal division; they have various types of divisions to facilitate growth and protection.

3. **Protoderm**: This is the outermost layer of the shoot apical meristem that gives rise to the epidermis of the plant. The protoderm cells divide anticlinally, which means they divide perpendicular to the surface, allowing for the expansion of the epidermis while maintaining its thickness.

4. **Phallogen**: This is a type of lateral meristem that contributes to the formation of the periderm (the protective outer layer of stems and roots). Phallogen typically divides tangentially, which means it divides parallel to the surface, producing cells on both the inner and outer sides.

After analyzing all the options, we conclude that:

- The **correct answer** is **Protoderm** because it always divides by anticlinal cell division to form the unithereate epidermis.

### Step-by-Step Solution:
1. **Identify the cell types**: Look at the options given: fusiform initial cells, root cap, protoderm, and phallogen.
2. **Understand the division types**: Recall the definitions of anticlinal (perpendicular to the surface) and periclinal (parallel to the surface) divisions.
3. **Analyze each option**:
- Fusiform initial cells: Divide periclinally.
- Root cap: Does not consistently divide anticlinally.
- Protoderm: Divides anticlinally to form the epidermis.
- Phallogen: Divides tangentially.
4. **Select the correct answer**: Based on the analysis, the protoderm is the only cell type that always divides by anticlinal cell division.