Vexillum is

Options

A. Posterior largest petal
B. Anterior largest petal
C. Found in pea family
D. both 1 & 3

Answer

**Step-by-Step Solution:**

1. **Understanding Vexillum**: Vexillum is a term used to describe a specific part of a flower, particularly in the context of the papilionaceous flower structure, which is commonly seen in the pea family (Fabaceae).

2. **Identifying the Structure**: In a papilionaceous flower, the corolla is composed of five petals. Among these, the vexillum is the largest petal, which is located at the back (posterior) of the flower.

3. **Characteristics of Vexillum**: The vexillum is also referred to as the standard petal. It is the most prominent petal in the flower and plays a crucial role in attracting pollinators.

4. **Other Petals in Papilionaceous Flowers**: In addition to the vexillum, there are two lateral petals known as wings and a pair of smaller petals that are fused together, forming the keel or carina.

5. **Examples**: Common examples of flowers that exhibit this structure include peas, beans, and gram (chickpeas), which are all part of the pea family (Fabaceae).

6. **Answering the Question**: The question asks what vexillum is. The correct options are:
- It is the posterior largest petal (True).
- It is found in the pea family (True).
- It is the anterior largest petal (False).

7. **Conclusion**: Therefore, the correct answer is option four: "both one and three" (posterior largest petal and found in the pea family).