Taxonomic Keys

Taxonomic keys are used to identify animals and plants. These are structured decision-making tools comprising a set of contradictory or contrasting statements or even propositions, which require the identifier to compare and make decisions given the statements in the key and associated with the entity to be identified.

A couplet is a way to quickly identify an unknown entity by providing two conflicting statements, one of which must be accepted and the other rejected. Each pair of contradictory characters is referred to as a couplet, and each statement within the couplet is referred to as a lead. By making the correct choice at each level, one can accurately identify the name of the plant or entity.

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How To Use Keys?

Read the introductory comments carefully

It is important to select the appropriate keys from manuals, floras, handbooks, monographs, etc. For example, cultivated plants are not usually found in floras, so manuals should be used in such cases.

Before you make a choice, carefully read and understand both the options. At times, the second option may be more suitable than the first.

Check the meaning of unknown terms with the help of a glossary.

Many specimens/materials would be necessary to measure when measuring fruit and leaves.

Avoid making decisions based solely on one observation.

Verify and validate results by comparing the description, specimens, and illustration with an authentic herbarium specimen.

How are Keys Constructed?

Always use constant characters; do not use variables.

Always use positive terms. For example, say “petiole is present” instead of “petiole is not present”.

Take precise measurements, avoiding terms such as ‘small’ and ’large’

Opt for characters that are always available instead of seasonal ones.

Make it a point to start both choices of a pair with the same word. For example: flower zygomorphic, flower actinomorphic (symmetry of flowers)

Begin exploring different options by using different terminology.

What are some disadvantages of using Taxonomic keys?

While taxonomic keys may assist in the quick identification of unknown entities, they do have certain disadvantages as well, such as:

The key that is used may not be able to capture all the properties and variations that a species exhibits. In other words, a single word or a few words may not be enough to accurately represent all the characteristics of the species - variations between species may not be adequately described.

It can be based on traits which are not visible during the season.

It is possible that not all of the species of interest or desired species are included.

There is a tendency to make mistakes when making a choice, and one wrong decision can lead to an incorrect interpretation.

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NEET NCERT Solutions (Biology)

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