Descending imbricate aestivation occurs in the corolla of

Options

A. Tamarindus
B. Cassia
C. Pisum
D. Helianthus.

Answer

To solve the question regarding which plant exhibits descending imbricate aestivation in its corolla, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Aestivation**:
- Aestivation refers to the arrangement of petals and sepals in a flower bud before it opens. It is important to know the different types of aestivation to answer the question correctly.

**Hint**: Remember that aestivation is all about how flower parts are arranged before blooming.

2. **Identify Types of Aestivation**:
- There are several types of aestivation, including valvate, imbricate, and descending imbricate. In descending imbricate aestivation, the petals overlap in a specific manner.

**Hint**: Focus on the characteristics of descending imbricate aestivation, particularly how the petals overlap.

3. **Describe Descending Imbricate Aestivation**:
- In descending imbricate aestivation, the posterior petal overlaps one margin of the two lateral petals, and these lateral petals then overlap the anterior petals, which are often united. This creates a descending order of overlap.

**Hint**: Visualize the arrangement of petals to better understand how they overlap in this type of aestivation.

4. **Examine the Given Options**:
- The options provided are Tamarindus, Cassia, Pecium, and Helianthus. We need to determine which of these exhibits descending imbricate aestivation.

**Hint**: Recall any specific examples or characteristics of the flowers from these options that might relate to the type of aestivation.

5. **Identify the Correct Plant**:
- After analyzing the options, it is established that descending imbricate aestivation is found in the corolla of Pecium (specifically in the genus Bison).

**Hint**: If you are unsure, consider looking up each plant to see their floral characteristics and confirm their type of aestivation.

### Final Answer:
Descending imbricate aestivation occurs in the corolla of **Pecium**.