Assertion: Scientific names have been standardized through ICBN.
Reason: First international botanical congress was held in Paris in 1967.

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that "Scientific names have been standardized through ICBN." The ICBN stands for the International Code of Botanical Nomenclature, which is indeed responsible for the standardization of scientific names of plants.

2. **Evaluating the Reason**: The reason given is "First international botanical congress was held in Paris in 1967." This statement is incorrect. The first International Botanical Congress actually took place in Belgium in 1864, not in Paris in 1967.

3. **Determining the Truth of Each Statement**:
- The assertion is **true** because the ICBN has standardized scientific names.
- The reason is **false** because the first International Botanical Congress was held in 1864 in Belgium, not in 1967 in Paris.

4. **Conclusion**: Since the assertion is true but the reason is false, we conclude that the assertion stands correct on its own without the support of the reason provided.

### Final Answer:
- **Assertion**: True
- **Reason**: False
- Therefore, the correct relationship is that the assertion is true, but the reason is not a correct explanation of the assertion.