Key is another taxonomical aid used for identification of plants and animals based on the
similarities and dissimilarities. The keys are based on the contrasting characters
generally in a pair called couplet. It represents the choice made between two opposite
options. This results in acceptance of only one and rejection of the other. Each statement
in the key is called a lead. Separate taxonomic keys are required for each taxonomic
category such as family, genus and species for identification purposes. Keys are
generally analytical in nature.
Flora, manuals, monographs and catalogues are some other means of recording
descriptions. They also help in correct identification. Flora contains the actual account
of habitat and distribution of plants of a given area. These provide the index to the plant
species found in a particular area. Manuals are useful in providing information for
identification of names of species found in an area. Monographs contain information on
any one taxon.