Keys help you find the likely description of your specimen rapidly and simply. Most keys are arranged to present you with a series of choices (decision points), usually dichotomous (dividing in two).
The paired statements of each ‘couplet’ are framed to be contrasting and mutually exclusive. Each choice you make narrows down the possibilities for your specimen until you find the appropriate description. Terminology is precise and brief. Keys can vary in complexity. An example of dichotomous keys can be found here:
NZ Gastrodia key
Recently, in addition to dichotomous keys, electronic computer-based keys are now being developed and used. Some New Zealand examples of electronic keys are:
NZ Coprosma key - Landcare Research
NZ grass key - Landcare Research
National Pest Plant Accord key - Landcare Research
Anonymous. 1957. Construction of key for the genus Nothofagus. Auckland Botanical Society Journal, 14: 2-3