Aerial stem modification found in Bougainvillea

Options

A. Spine
B. Thorn
C. Tendril
D. Hook

Answer

### Step-by-Step Solution:

1. **Understanding Aerial Stem Modifications**:
Aerial stem modifications refer to changes in the structure of the stem that occur above the ground. These modifications can serve various functions such as climbing, protection, and support.

2. **Identifying Bougainvillea**:
Bougainvillea is a flowering plant known for its vibrant colors and climbing nature. It is important to identify the specific modification that occurs in this plant.

3. **Recognizing the Modification in Bougainvillea**:
In Bougainvillea, the axillary buds of the plant develop into thorns. This is a key characteristic of the plant and serves the purpose of protection.

4. **Differentiating Between Other Modifications**:
- **Spines**: These are modifications of leaves for defense.
- **Tendrils**: These are modifications of leaf tips or stipules that help in climbing.
- **Hooks**: These are also modifications of leaves, adapted for climbing.

5. **Conclusion**:
The aerial stem modification found in Bougainvillea is specifically thorns, which are derived from axillary buds.

### Final Answer:
The aerial stem modification found in Bougainvillea is **thorns**.