in monocot stem, each vascular bundle possesses a lacuna which is formed by disintegration of

Options

A. protophloem
B. protoxylem
C. metaphloem
D. metaxylem

Answer

**Step-by-Step Solution:**

1. **Understanding Vascular Bundles in Monocots**: In monocot stems, vascular bundles are arranged in a scattered manner. Each vascular bundle consists of xylem and phloem tissues.

2. **Identifying the Components**: The xylem is responsible for water and mineral transport, while phloem transports food. Within the xylem, there are two types: protoxylem and metaxylem.

3. **Formation of Protoxylem and Metaxylem**: Protoxylem is the first xylem to develop, followed by metaxylem. Protoxylem cells are typically smaller and more delicate than metaxylem cells.

4. **Disintegration of Protoxylem**: In monocot stems, as the plant grows, the protoxylem cells undergo disintegration. This disintegration creates a space or cavity within the vascular bundle.

5. **Lacuna Formation**: The cavity formed by the disintegration of protoxylem cells is referred to as a lacuna. This lacuna is also known as protoxylem lacunae.

6. **Function of the Lacuna**: The lacuna serves as a storage space for water, thus it is sometimes called a water cavity. It is important for the plant's hydration and nutrient transport.

7. **Conclusion**: Therefore, the lacuna in the vascular bundles of monocot stems is formed by the disintegration of protoxylem cells.

**Final Answer**: The correct option is protoxylem.

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