Some plants of arid region modify their stems into flattened (Opuntia), or fleshy cylindrical (Euphorbla) green structures called

Options

A. Phyllode
B. Rhizome
C. Phylloclade
D. Stem tendrils

Answer

### Step-by-Step Solution:

1. **Identify the Plants**: The question mentions two specific plants from arid regions: Opuntia and Euphorbia.

2. **Understand Stem Modifications**: In arid environments, plants often face water scarcity. To adapt, they modify their stems to perform photosynthesis and conserve water.

3. **Describe the Modifications**:
- **Opuntia**: This plant has a flattened stem structure.
- **Euphorbia**: This plant has a fleshy cylindrical stem structure.

4. **Define the Green Structures**: Both of these modified stems are adaptations that help the plants survive in dry conditions.

5. **Name the Structures**: The modified green structures of the stems in these plants are called **phylloclades**.

6. **Conclude the Answer**: Therefore, the answer to the question is that the modified stems of Opuntia and Euphorbia are called **phylloclades**.