Thorns are found in plants like Citrus and Bougainvillea.

Explanation

**Step-by-Step Solution:**

1. **Identify the Statement**: The statement is that thorns are found in plants like Citrus and Bougainvillea.

2. **Understanding Thorns**: Thorns are specialized structures that are modified stems. They serve as a defense mechanism for the plant.

3. **Examples of Plants with Thorns**: Citrus (such as lemon and orange trees) and Bougainvillea are both known to have thorns on their stems.

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