Illinois Natural History Survey - University of Illinois

The Naturalist's Apprentice: What Tree is That?

 Objective: to acquaint students with the concept of biological keys


Materials: multiple copies of What Tree Is That?, leaves from various trees found in the key


Vocabulary: biological key, dichotomous, systematist, taxonomist


Comments: Scientists who locate, describe, name, and determine the relationships of species of organisms to other species are called taxonomists or systematists. To identify organisms, these scientists assemble taxonomic information and arrange it in a logical form called a key. Although there are dozens of types of keys, we will use the dichotomous key, dich meaning two parts and tomous to divide. Thus, a dichotomous key consists of two choices that have other choices associated with them. Students will construct a key to the leaves of the most common types of trees.



1. Have students learn the various types of leaves and become familiar with the key.

2. Students then try to identify the three unknown samples at the bottom of the activity. Answers: oak, maple, yellowwood. 

3. Bring in leaves from the various type of trees found in the key and have students attempt to identify each from actual specimens.


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