Number of orthostichies present in opposite and decussate phyllotaxy is

Options

A. Two
B. Four
C. One
D. Three.

Answer

To solve the question regarding the number of orthostichies present in opposite and decussate phyllotaxy, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Phyllotaxy**: Phyllotaxy refers to the arrangement of leaves on the stem. It can be classified into three main types: alternate, opposite, and whorled.

2. **Identify Opposite Phyllotaxy**: In opposite phyllotaxy, two leaves arise at each node, positioned directly opposite each other.

3. **Differentiate Between Types of Opposite Phyllotaxy**: Opposite phyllotaxy can be further divided into two categories:
- **Decussate Phyllotaxy**: Here, each pair of leaves is arranged perpendicular to the previous pair.
- **Superposed Phyllotaxy**: In this arrangement, the pairs of leaves are stacked directly on top of each other.

4. **Define Orthostichies**: Orthostichies are defined as the vertical rows of leaves along the stem.

5. **Determine the Number of Orthostichies**: In the case of decussate phyllotaxy, there are only two orthostichies present. This is because the leaves are arranged in pairs that alternate at right angles to each other, resulting in two distinct vertical rows.

6. **Conclusion**: Therefore, the number of orthostichies present in opposite and decussate phyllotaxy is **2**.

### Final Answer:
The correct answer is **2** orthostichies.

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