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?
The friend would explain to him that a key is used to study the taxonomic categories, and it comprises of two contrasting characters. These characters exist in pairs, and these pairs are called couplets. The examination of a key makes it possible to either accept or reject the contrasting characters. The statements in a key are called the leads, and the choice of the contrasting characters is made in a key. The key is analytic in nature, and they are different for each different taxonomic level. The keys are important for the identification of the given organisms. For instance, is an organism that has a notochord or not will define whether the organism belongs to invertebrata or sub-phylum vertebrata. Another example could be the presence of lungs which determines it the organism is from the Tetrapoda group or the Pisces.