In which of the following inflorescence fleshy receptacle forms a hollow cavity with an apical opening and flowers are developed on inner wall of the hollow cavity ?

Options

A. Cyathium
B. Capitate
C. Hypanthodium
D. Verticillaster

Answer

To solve the question regarding the type of inflorescence where a fleshy receptacle forms a hollow cavity with an apical opening, and flowers develop on the inner wall of this cavity, we can proceed step by step as follows:

### Step-by-Step Solution:

1. **Understand the Question**: We need to identify an inflorescence type characterized by a fleshy receptacle that creates a hollow cavity with an opening at the top, where flowers grow on the inner walls.

2. **Evaluate the Options**: The question provides multiple options. We will analyze each option to see if it fits the description provided.

3. **Analyze the First Option - Sainthium**:
- Sainthium has a structure where male flowers surround female flowers but does not have a hollow cavity or an apical opening. Therefore, it does not fit the criteria.

4. **Analyze the Second Option - Capitate (Capitulum)**:
- Capitate inflorescence (Capitulum) has a flat receptacle with many small florets. However, it does not have a fleshy receptacle or a hollow cavity. Thus, this option is also not suitable.

5. **Analyze the Third Option - Hypanthodium**:
- Hypanthodium is characterized by a fleshy receptacle that forms a hollow cavity. It has an apical opening known as an ostiole, and flowers develop on the inner walls of this cavity. Male flowers are located near the opening, while female flowers are found at the bottom. This matches the description in the question perfectly.

6. **Conclusion**: Based on the analysis, the correct answer is Hypanthodium, as it fulfills all the conditions mentioned in the question.

### Final Answer:
**Hypanthodium**