Tertiary wall is known from

Options

A. Compression wood of dicots
B. Tension wood of gymnosperms
C. Cotton fibres
D. All hard woods

Answer

### Step-by-Step Solution:

1. **Understanding the Tertiary Wall**: The tertiary wall is the innermost layer of the cell wall in plants. It is important to note that it is distinct from the primary and secondary walls.

2. **Composition of the Tertiary Wall**: The tertiary wall is primarily composed of lignin and xylene. Unlike the primary and secondary walls, it does not contain cellulose.

3. **Characteristics of the Tertiary Wall**: The tertiary wall is thinner compared to the other layers. Its structure plays a crucial role in the mechanical properties of the plant.

4. **Function of the Tertiary Wall**: The tertiary wall is associated with the formation of compression wood, which is a type of wood that provides support to the plant, especially in gymnosperms. Compression wood is known for being dense and heavy.

5. **Relation to Gymnosperms**: In gymnosperms, the compression wood is referred to as tension wood. This indicates that the tertiary wall is particularly significant in the context of gymnosperm trees.

6. **Conclusion**: Therefore, the tertiary wall is known for its role in the formation of compression wood, which is specifically associated with gymnosperms.

### Final Answer:
The tertiary wall is known from gymnosperms, specifically for its role in the formation of compression wood.

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