A species which was introduced for ornamentation but has become a trouble some weed in India:

Options

A. Parthenium hysterophorus
B. Eichhornia crassipes
C. Prosopis juliflora
D. Trapa spinosa

Answer

To solve the question regarding a species that was introduced for ornamentation but has become a troublesome weed in India, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for a plant species that was brought to India for decorative purposes but later became a problematic weed.

2. **Identify the Options**: The options provided include various plant species. We need to analyze each one to determine its origin and behavior in India.

3. **Analyze Each Option**:
- **Parthenium hysterophorus**: This plant is known as Santa Maria Feverfew and is native to the American tropics. Although it is introduced in India, it is not primarily known as a troublesome weed in the same sense as others.

- **Eichhornia crassipes**: Commonly known as water hyacinth, this plant is native to the Amazon Basin. It was introduced to India for ornamental purposes but has indeed become a significant troublesome weed, clogging waterways and affecting aquatic ecosystems.

- **Prosopis juliflora**: This species is also native to the Americas and was introduced to India. However, it is more recognized for being a troublesome weed in Africa rather than in India specifically.

- **Tamarindus indica (Tamarind)**: This is a native plant of India and not introduced, so it cannot be the answer.

4. **Select the Correct Answer**: Based on the analysis, **Eichhornia crassipes (water hyacinth)** is the correct answer as it fits the criteria of being introduced for ornamentation and becoming a troublesome weed in India.

### Final Answer:
The species that was introduced for ornamentation but has become a troublesome weed in India is **Eichhornia crassipes (water hyacinth)**.

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