A student of taxonomy was puzzled when told by his professor to look for a key to identify a plant. He went to his friend to clarify what ‘Key’ the professor was referring to? What would the friend explain to him?

In the given reference, a ‘key’ is a taxonomical aid. A key is used to identify plants and animals based on their similarities and dissimilarities. The keys made are based on the contrasting characters that are depicted by the organisms, these are known as couplets.

A key represents the choice made between two given options opposite in nature. The comparison of the contrasting characters results in acceptance of one and the rejection of another. Keys are generally analytical in nature.