A modification of petiole is -

Options

A. Cladode
B. Phylloclade
C. Phyllode
D. Pistillode

Answer

**Step-by-Step Solution:**

1. **Understanding Petiole**: The petiole is the stalk that attaches the leaf blade to the stem of the plant. It plays a crucial role in supporting the leaf and facilitating the transport of nutrients and water.

2. **Modifications of Petiole**: The petiole can undergo various modifications to adapt to the plant's environment. Some common modifications include tendrils, spines, spongy petioles, and winged petioles.

3. **Identifying the Correct Modification**: Among the options given (cladode, phyloclad, phyllode, and pistilode), we need to identify which one is a modification of the petiole.

4. **Defining Phyllode**: A phyllode is a green, flattened structure that is formed by the modification of the petiole or the rachis of the leaf. It resembles a leaf and performs photosynthesis.

5. **Function of Phyllode**: In xerophytic plants, where water conservation is essential, leaves may be reduced in size to minimize water loss. In such cases, the petiole can be modified into phyllodes to carry out photosynthesis, effectively taking over the leaf's function.

6. **Examples of Plants with Phyllodes**: Some examples of plants that exhibit phyllodes include Acacia and Opuntia. These plants have adapted to their environments by modifying their petioles into phyllodes.

7. **Conclusion**: Based on the definitions and functions discussed, the correct answer to the question "A modification of petiole is -" is **phyllode**.

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