Which one of the following is a wood-rotting fungus ?

Options

A. Agaricus
B. Lycoperdon
C. Morchella
D. Polyporus

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for a specific type of fungus known as a wood-rotting fungus. This means we need to identify a fungus that is known to decay or damage wood.

2. **Definition of Wood-Rotting Fungus**: A wood-rotting fungus is a type of fungus that breaks down wood material, often leading to decay. These fungi can either be saprophytic (feeding on dead organic matter) or parasitic (feeding on living trees).

3. **Identifying Wood-Rotting Fungi**: One of the most well-known wood-rotting fungi is from the genus *Polyporus*, which is also referred to as bracket fungus. This genus belongs to the family Polyporaceae.

4. **Habitat and Behavior**: *Polyporus* fungi can grow on dead or decayed trees as saprophytes or can act as parasites on the roots or trunks of living trees. They are known to attack various types of trees, including conifers, oaks, apple trees, walnut trees, and pear trees.

5. **Symptoms of Wood Rot**: The presence of wood-rotting fungi can be identified by the appearance of small rots on the surface of the stems or roots of the affected trees, indicating damage and decay.

6. **Evaluating Options**: The options provided include:
- Agaricus (incorrect)
- Lycoperdon (incorrect)
- Marshallia (incorrect)
- Polyporus (correct)

7. **Conclusion**: Based on the information gathered, the correct answer to the question is *Polyporus*, as it is the wood-rotting fungus that causes decay in various types of trees.