Thorn of Citrus is

Options

A. Leaf modification
B. Stem modification
C. Root modification
D. Petiole modification

Answer

### Step-by-Step Text Solution:

1. **Identify the Question**: The question asks about the nature of the thorn in Citrus plants.

2. **Understand Plant Modifications**: Thorns are a type of plant modification. They are hard, pointed structures that serve specific functions in plants.

3. **Function of Thorns**: Thorns primarily serve as a protective measure for the plant. They deter herbivores and other predators from consuming the plant or its fruits.

4. **Thorns in Citrus Plants**: In Citrus plants, such as oranges and lemons, thorns are specifically developed from a modified stem. This means that the stem of the plant undergoes a transformation to become a thorn.

5. **Characteristics of Thorns**: The thorns in Citrus are long, sharp, and pointed. They not only serve to protect the plant but also help in reducing the rate of transpiration, which is the process of water loss from the plant.

6. **Conclusion**: Therefore, the thorn of Citrus is classified as a type of stem modification.

### Final Answer:
The thorn of Citrus is a type of stem modification.

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