Which of the following is generally present in dicot stem ?
(i) Endodermis (ii) Pericycle (iii) Medullary ray (iv) Phloem parenchyma (v) pith (vi) Epidermis

Options

A. All except (iii) and (iv)
B. All except (iv)
C. All except ( i ) and (iii)
D. All except (iv)

Answer

To determine which of the following structures is generally present in a dicot stem, we will analyze each option provided:

1. **Endodermis**: The endodermis is a layer of cells that surrounds the vascular tissue in roots and stems. In dicot stems, it is usually present, so this option is valid.

2. **Pericycle**: The pericycle is a layer of cells that can give rise to lateral roots and is present in dicot stems. Therefore, this option is also valid.

3. **Medullary ray**: Medullary rays are strands of parenchyma cells that extend radially between the xylem and phloem in the vascular bundles. They are typically found in dicot stems, making this option valid as well.

4. **Phloem parenchyma**: Phloem parenchyma is a type of parenchyma tissue found in the phloem. However, it is not a distinct structure that is typically referenced when discussing the anatomy of dicot stems. This option is not generally considered present in dicot stems.

5. **Pith**: The pith is the central part of the stem, composed of parenchyma cells. It is present in dicot stems, so this option is valid.

6. **Epidermis**: The epidermis is the outermost layer of cells covering the stem. It is present in dicot stems, making this option valid.

Now, summarizing the valid structures present in a dicot stem:
- Endodermis: Present
- Pericycle: Present
- Medullary ray: Present
- Phloem parenchyma: Not generally present
- Pith: Present
- Epidermis: Present

Thus, the correct answer to the question is **(iv) Phloem parenchyma**, as it is the only option that is not generally present in dicot stems.