In earlier systems of classification basis of classification of plants were all of the following except:

Options

A. Root modifications
B. Leaf venation
C. Natural affinities
D. Number of cotyledons

Answer

To solve the question regarding the bases of classification of plants in earlier systems, we will analyze each option provided:

1. **Root Modifications**: In earlier classification systems, plants were often classified based on their root structures. Different types of roots (like tap roots, fibrous roots, etc.) were considered important for classification. Therefore, this option is a valid basis for classification.

2. **Leaf Venation**: Leaf venation refers to the pattern of veins in leaves. This characteristic was also used in earlier classification systems to differentiate between plant groups (for example, parallel vs. reticulate venation). Thus, this option is also a valid basis for classification.

3. **Natural Affinities**: This term refers to the inherent relationships and similarities between different plant species based on their ecological and environmental interactions. However, natural affinities were not a specific criterion used in the earlier systems of classification. Therefore, this option is not a valid basis for classification.

4. **Number of Cotyledons**: The number of cotyledons (seed leaves) is a fundamental characteristic used to classify plants into monocots (one cotyledon) and dicots (two cotyledons). This classification is widely recognized and used in both earlier and modern systems. Thus, this option is a valid basis for classification.

After analyzing all the options, we conclude that the basis of classification of plants that was not used in earlier systems is:

**Correct Answer: Natural Affinities (Option 3)**