Papilionaceous flower with large vexillum covering two wings and the wings covering the keel has corolla aestivation of

Options

A. Descending imbricate
B. Ascending imbricate
C. Twised
D. Vexillary.

Answer

To answer the question regarding the corolla aestivation of a papilionaceous flower with a large vexillum covering two wings and the wings covering the keel, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Papilionaceous Flowers**:
- Papilionaceous flowers are characteristic of the Fabaceae family (legumes). They typically have a specific arrangement of petals.

2. **Identifying the Parts of the Flower**:
- In a papilionaceous flower, the petals are divided into:
- **Vexillum**: The large upper petal.
- **Wings**: Two lateral petals that are positioned on either side of the vexillum.
- **Keel**: The two lower petals that are fused together, forming a boat-like structure.

3. **Recognizing the Aestivation Pattern**:
- Aestivation refers to the arrangement of petals in a flower bud before it opens.
- In papilionaceous flowers, the arrangement is such that the vexillum covers the wings, and the wings cover the keel.

4. **Determining the Type of Aestivation**:
- The specific arrangement described (vexillum covering the wings and wings covering the keel) corresponds to the **vexillary type of aestivation**.
- This can be represented in a floral formula as 1 + 2 + 2, where:
- 1 represents the vexillum,
- 2 represents the wings,
- 2 (in brackets) represents the fused keel petals.

5. **Conclusion**:
- Therefore, the corolla aestivation of a papilionaceous flower with a large vexillum covering two wings and the wings covering the keel is classified as **vexillary aestivation**.

### Final Answer:
The corolla aestivation of the described papilionaceous flower is **vexillary**.

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