A diagnostic trait for identification of fabaceous flower is

Options

A. Tetradynamous androecium
B. Inferior ovary
C. Cruciform corolla
D. Vexillary aestivation.

Answer

To identify a diagnostic trait for Fabaceous flowers, we can analyze the options provided in the question step by step.

### Step 1: Understand the Family Fabaceae
The Fabaceae family, also known as the legume family, includes a variety of flowering plants. It is important to know the common characteristics of flowers in this family to identify them correctly.

### Step 2: Analyze Each Option
1. **Tetradynamous Androsium**: This term refers to having six stamens, where four are long and two are short. This trait is characteristic of the Brassicaceae family, not Fabaceae. Therefore, this option is incorrect.

2. **Inferior Ovary**: In Fabaceae, the ovary is typically superior, meaning it is positioned above the attachment of other floral parts. Thus, this option is also incorrect.

3. **Cruciform Corolla**: A cruciform corolla, which means having a cross-shaped flower, is not a defining trait of Fabaceae. Instead, Fabaceae flowers are often described as having a distinct arrangement of petals. Therefore, this option is incorrect.

4. **Baxillary Estivation**: This refers to the arrangement of petals in the flower. In Fabaceae, the petals are arranged such that the largest petal (the standard) is at the back, covering the two lateral petals, which in turn cover the two smaller anterior petals. This is indeed a characteristic feature of Fabaceous flowers.

### Conclusion
Based on the analysis, the correct answer is **baxillary estivation**, which is option number four.

### Final Answer
The diagnostic trait for identification of Fabaceous flowers is **baxillary estivation**.

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