Underground stem that has contractile roots

Options

A. Rhizome
B. Corm
C. Stem tuber
D. Bulb

Answer

To solve the question "Underground stem that has contractile roots," we need to analyze the given options: rhizome, corm, stem tuber, and bulb.

### Step-by-Step Solution:

1. **Understanding the Question**: We need to identify an underground stem that possesses contractile roots. Contractile roots are specialized roots that help in pulling the plant deeper into the soil.

2. **Analyzing the Options**:
- **Rhizome**: This is an underground stem that grows horizontally. It is found in plants like ginger. However, rhizomes do not have contractile roots. Thus, this option is incorrect.
- **Corm**: A corm is a swollen underground stem that grows vertically. It has a spherical node and internodes similar to a typical stem. Corms are known to have contractile roots, which help in pulling the corm deeper into the soil. This option is correct.
- **Stem Tuber**: Stem tubers, like those found in potatoes, are also underground stems but they do not have contractile roots. Therefore, this option is incorrect.
- **Bulb**: A bulb is a modified stem that has a reduced structure with fleshy scaly leaves. Bulbs do not possess contractile roots, making this option incorrect as well.

3. **Conclusion**: After analyzing all the options, the only underground stem that has contractile roots is the corm.

### Final Answer:
The correct answer is **B) Corm**.