Which of the following pairs is incorrectly matched?

Options

A. Plum-Perigynous fower
B. Striga - Collects water and minerals from the endarch xylem of host
C. Euphorbia - Fleshy cylindrical phylloclades
D. Alstonia - More than two leaves at each node

Answer

To determine which of the given pairs is incorrectly matched, we will analyze each option based on the definitions and characteristics of the terms involved.

### Step-by-Step Solution:

1. **Understanding Periginous Flowers**:
- Periginous flowers are those where the ovary is half inferior. In this case, the other floral parts are situated at the same level as the rim of the thalamus.
- Example: **Plum** is correctly identified as a periginous flower.

2. **Understanding Endarch Xylem**:
- Endarch xylem is a type of xylem arrangement where the protoxylem is located towards the center (inner side) and the metaxylem is located towards the periphery (outer side), typically found in the stems of plants.
- **Striga**, a parasitic plant, collects nutrients from the roots of its host plant. Since it is a root parasite, it interacts with the xylem of the roots.

3. **Identifying the Incorrect Pair**:
- The statement that "Striga collects water and minerals from endarch xylem" is incorrect because Striga, being a root parasite, would interact with the xylem in the roots, which is typically exarch (where the protoxylem is on the outside and metaxylem is on the inside).
- Therefore, this pair is incorrectly matched.

4. **Verifying Other Options**:
- **Euphorbia** is mentioned as having fleshy cylindrical phylloclades, which is correct since phylloclades are modified stems that perform photosynthesis.
- **Elstonia** is noted for having more than two leaves at each node, which corresponds to whorled phyllotaxy, and this is also correct.

5. **Conclusion**:
- The only incorrect pair is the one involving Striga and endarch xylem.

### Final Answer:
The incorrectly matched pair is **Striga - Endarch Xylem**.

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