Which type of vascular bundles are found in the primary internal structure of dicotyledonae stem (eg. Sunflower stem)?

Answer

To answer the question regarding the type of vascular bundles found in the primary internal structure of dicotyledonous stems, such as the sunflower stem, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Type of Plant**:
- We are dealing with dicotyledonous plants (dicots), which have specific structural characteristics.

2. **Understand Vascular Bundles**:
- Vascular bundles are the structures that contain xylem and phloem, responsible for the transport of water, nutrients, and food.

3. **Arrangement of Vascular Bundles**:
- In dicots, the vascular bundles are arranged in a ring formation. This is a distinctive feature of dicot stems.

4. **Characteristics of Vascular Bundles**:
- **Open**: The vascular bundles are termed "open" because they contain cambium tissue, which allows for secondary growth.
- **Conjoined**: The xylem and phloem are located at the same radius from the center, meaning they are adjacent to each other in the vascular bundle.
- **Endarch**: The xylem is positioned towards the center (pith) of the stem, while the phloem is located outside of the xylem.

5. **Conclusion**:
- Therefore, the vascular bundles in the primary internal structure of a dicotyledonous stem, such as that of a sunflower, are characterized as open, conjoined, and endarch.

### Final Answer:
The vascular bundles found in the primary internal structure of dicotyledonous stems (e.g., sunflower stem) are **open, conjoined, and endarch**.

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