Which structure of petals encloses the stamen and pistil.

Answer

**Step-by-Step Solution:**

1. **Understanding Flower Structure**: In flowering plants, the reproductive structures are the stamen (male) and the pistil (female). It's important to identify where these structures are located within the flower.

2. **Identifying Petal Types**: Flowers can have different types of petals. In the case of papilionaceous flowers (commonly found in legumes), the petals are arranged in a specific way.

3. **Recognizing the Keel Petal**: In papilionaceous flowers, the petals are divided into three main types:
- The **banner** (or vexillum), which is the large upper petal.
- The **wings**, which are two smaller lateral petals.
- The **keel petals**, which are two smaller petals that are located below the wings.

4. **Function of the Keel Petal**: The keel petals are crucial as they enclose the reproductive structures of the flower, specifically the stamen and pistil. This is the key characteristic that answers the question.

5. **Conclusion**: Therefore, the structure of petals that encloses the stamen and pistil is known as the **keel petal**.

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