Lesson 4: Identifying Trees

Imagine that you have been given the task of identifying the trees of a particular forest ecosystem. How would you proceed with such an enormous task?

Fortunately, biologists have a special tool to assist them with identification of different species. This tool, known as a dichotomous key, is a series of questions.

In essence, using a dichotomous key is similar to playing the game "twenty questions." Each question of a dichotomous key asks you to examine the specimen and make a choice between two possible answers. This allows a biologist to identify a species by eliminating characteristics that do not apply to it. Making a choice about a particular characteristic leads to a new branch of the key. Eventually the user will be led to the name of the organism being identified.