Citrus thorn/spine is actually modification of

Options

A. Stem
B. Branch
C. Leaf
D. Stipule

Answer

To solve the question "Citrus thorn/spine is actually a modification of?", we will analyze the options provided and understand the nature of thorns in plants.

### Step-by-Step Solution:

1. **Understanding Thorns**:
- Thorns are hard, woody, and pointed structures that serve primarily for protection against herbivores. They can also help reduce water loss by minimizing transpiration.

2. **Identifying the Modification**:
- In various plants, different parts can be modified into thorns. For example:
- In Bougainvillea and Duranta, the axillary buds are modified into thorns.
- In Carissa, the terminal bud is modified into pairs of thorns.

3. **Function of Thorns**:
- The main function of thorns is protection, but they can also play a role in reducing transpiration.

4. **Analyzing the Options**:
- **Option 1: Stem** - Thorns can be modified stems, as seen in many plants.
- **Option 2: Branch** - While branches can also be modified, thorns specifically relate to stem modifications.
- **Option 3: Leaf** - Leaves can be modified into spines (like in cacti), but thorns are not typically leaf modifications.
- **Option 4: Stipule** - Stipules are small leaf-like structures at the base of a leaf stalk and are not related to thorns.

5. **Conclusion**:
- Based on the analysis, the correct answer is **Option 1: Stem**. Citrus thorns are modifications of the stem.

### Final Answer:
Citrus thorn/spine is actually a modification of **stem**.

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