The vascular bundlies in the stems of several dicots are conjoint, collateral, and open. In each of these bundles,

Options

A. Xylem and phloem are on the same radius with phloem towards the pith and xylem towards the pericycle without a strip of cambium between them
B. Xylem and phloem are on the same radius with xylem towards the pith and phloem towards the pericycle and a strip of combium separtes the two
C. Xylem completely surroundds the phloem on all sides but the two are separted by the cambium
D. Phloem completely surrounds the xylem and a strip of combium separtes the two

Answer

To solve the question regarding the arrangement of vascular bundles in the stems of dicots, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Vascular Bundles**:
- Vascular bundles in dicots are described as "conjoint," "collateral," and "open."
- "Conjoint" means that both xylem and phloem are present together in the same bundle.
- "Collateral" indicates that the xylem and phloem are arranged on the same radius of the stem.

2. **Identifying Open vs. Closed Bundles**:
- "Open" vascular bundles have a vascular cambium present between the xylem and phloem. This allows for secondary growth.
- In contrast, closed bundles lack this cambium and do not allow for secondary growth.

3. **Arrangement of Xylem and Phloem**:
- In a typical dicot stem, the arrangement is such that:
- Phloem is located on the outer side (towards the bark).
- Xylem is located on the inner side (towards the center of the stem).
- The cambium is situated between the xylem and phloem.

4. **Evaluating the Options**:
- We need to analyze the given options based on the above understanding:
- **Option A**: Xylem and phloem are on the same radius with phloem towards the pith. (Incorrect)
- **Option B**: Xylem and phloem are on the same radius with xylem towards the width and phloem towards the pericycle, separated by cambium. (Correct)
- **Option C**: Xylem completely surrounds the phloem on all sides. (Incorrect)
- **Option D**: Phloem completely surrounds the xylem. (Incorrect)

5. **Conclusion**:
- The correct arrangement of vascular bundles in the stems of dicots is described in **Option B**: Xylem is towards the center (width) and phloem is towards the outer side (pericycle), with cambium in between.

### Final Answer:
- The correct option is **B**: Xylem and phloem are on the same radius with xylem towards the width and phloem towards the pericycle, separated by a strip of cambium.