Origin of lateral root of secondary root is
1 Endodermal cells against phloem
2 Pericycle cells against protoxylem
3 Cortical cells below root hairs
4 Epiblema/phellogen

Options

A. Endodermal cells against phloem
B. Pericycle cells against protoxylem
C. Cortical cells below root hairs
D. Epiblema/phellogen

Answer

To solve the question regarding the origin of lateral roots in secondary growth, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Root Structure**:
- First, we need to familiarize ourselves with the anatomy of a dicot root. The root consists of several layers: the outermost layer is the epidermis, followed by the cortex, endodermis, pericycle, xylem, and phloem.

2. **Identify the Layers**:
- The epidermis is the protective outer layer, while the cortex lies beneath it. The innermost layer of the cortex is called the endodermis, which is rich in suberin and forms the Casparian strip. Below the endodermis is the pericycle.

3. **Role of Pericycle**:
- The pericycle is a layer of cells that is crucial for the initiation of lateral roots. It consists of thick-walled parenchymatous cells and is located just inside the endodermis.

4. **Lateral Root Formation**:
- Lateral roots originate from the pericycle. Specifically, they emerge from the pericycle cells that are positioned against the protoxylem. This is a key point because the protoxylem is located at the periphery of the root.

5. **Evaluating Options**:
- Now, let's evaluate the provided options:
- **Option 1**: Endodermal cells against phloem - Incorrect, as lateral roots do not originate from the endodermis.
- **Option 2**: Pericycle cells against protoxylem - Correct, as this is the actual origin of lateral roots.
- **Option 3**: Cortical cells below root hairs - Incorrect, as lateral roots do not originate from the cortex.
- **Option 4**: Epiblema/phellogen - Incorrect, as these layers are not involved in the formation of lateral roots.

6. **Conclusion**:
- The correct answer is **Option 2: Pericycle cells against protoxylem**. This is where lateral roots originate during secondary growth.