In vexillary aestivation, posterior petal is known as________

Answer

To answer the question "In vexillary aestivation, the posterior petal is known as________", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Vexillary Aestivation**:
- Vexillary aestivation is a type of floral arrangement where the petals are arranged in a specific manner. It is commonly observed in the family Fabaceae (legumes).

2. **Identifying the Petals**:
- In vexillary aestivation, there are typically five petals. These include:
- One large posterior petal
- Two lateral petals
- Two smaller petals that are fused together at the base, forming a structure known as the keel.

3. **Recognizing the Posterior Petal**:
- The posterior petal is the largest petal in this arrangement and plays a significant role in the flower's structure.

4. **Naming the Posterior Petal**:
- The posterior petal in vexillary aestivation is specifically referred to as the "vexillum".
- It is also commonly known as the "standard".

5. **Final Answer**:
- Therefore, in vexillary aestivation, the posterior petal is known as **vexillum** (or standard).