Select the incorrect statement w.r.t. taxonomic aids.

Options

A. Key is based on set of contrasting characters known as couplet
B. There is no universally accepted system for the arrangement of herbarium sheets
C. Flora contains actual account of habitat and distribution of plants of a given area
D. Monographs contain information on any one taxon

Answer

To solve the question regarding taxonomic aids, we need to evaluate each statement provided in the options and determine which one is incorrect. Here’s a step-by-step breakdown:

### Step 1: Analyze the first statement
**Statement:** Keys based on a set of contrasting characters are known as couplets.

**Evaluation:** This statement is true. In taxonomy, a key is a tool that helps in identifying organisms based on contrasting characteristics, and these contrasting pairs of characters are indeed referred to as couplets.

### Step 2: Analyze the second statement
**Statement:** There is no universally accepted system for the arrangement of herbarium sheets.

**Evaluation:** This statement is incorrect. There are established guidelines for the arrangement of herbarium sheets, which are widely accepted in the scientific community. Therefore, this option is the one we are looking for.

### Step 3: Analyze the third statement
**Statement:** Flora contains an actual account of habitat and distribution of plants of a given area.

**Evaluation:** This statement is true. A flora is a comprehensive description of the plant species found in a particular area, including their habitats and distributions.

### Step 4: Analyze the fourth statement
**Statement:** Monographs contain information on any one taxon.

**Evaluation:** This statement is true. Monographs are detailed studies that focus on a single taxonomic group, providing extensive information about that particular taxon.

### Conclusion
After evaluating all the statements, we find that the second statement, "There is no universally accepted system for the arrangement of herbarium sheets," is the incorrect statement regarding taxonomic aids.

### Final Answer
The incorrect statement with respect to taxonomic aids is: **There is no universally accepted system for the arrangement of herbarium sheets.**

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