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A dichotomous key is a tool that can be used to identify trees or flowers, animals, rocks, fish, and more. “Dichotomous” means “divided into two parts.” Therefore, a dichotomous key will always give two choices in each step, and following all the steps will lead you to the name of the tree you’re identifying.

LEAF’s Online Dichotomous Tree ID Key

LEAF’s Printable Summer Tree ID Key & Tree ID Terms (Part of the LEAF Field Enhancement 1, Tree Identification)

LEAF’s Printable Winter Tree ID Key (uses buds, twigs, and other features to identify Wisconsin trees)
Tips for printing the Winter Tree Identification Key:

  • Choose “Landscape” page orientation​
  • Choose “Print on both sides”
  • Legal size paper works best, though Letter will also work
  • To ensure the pages print in booklet form, be certain the paper is flipping on the short side; if the second page is printing upside down, the pages are not flipping on the short side.

Urban Tree Key – (not dichotomous) Courtesy of the Wisconsin Department of Natural Resources – Division of Forestry

Lesson Ideas using Dichotomous Keys

Kevin Hall’s High School Lab :
A high school lab that Biology teacher Kevin Hall created using the LEAF Online Dichotomous Tree Key.

LEAF Field Enhancement 1 – Tree Identification :
In this lesson, students learn to use a dichotomous key to identify Wisconsin trees with LEAF’s Summer Tree ID Key.

LEAF’s Tree Identification Cards

Other Tree Identification Web Resources

American Forests’ Tree Doctor

Confused but curious about pruning? Baffled by bugs? Stumped by a tree ID? American Forests’ Tree Doctor is in and online. Send your tree-related questions to an expert at, and they’ll respond directly to you. 

Dichotomous Tree Key – EEK! Wisconsin Department of Natural Resources

This is the DNR’s tree ID site for kids. It utilizes descriptions and line drawings.

National Arbor Day Foundation

Detailed information on dozens of commonly planted landscape trees that grow throughout the United States as well as tree terms, forest layers, tree classification, and anatomy of tree.

National Arbor Day Foundation

Also, from the National Arbor Day Foundation, line drawings of tree leaves found throughout the U.S. and an animated “how to” identify trees guide.

Tree and Shrub Identification – Wisconsin Department of Natural Resources

Basic ID key with photos and descriptions of many Wisconsin tree species.

Trees of Wisconsin – Cofrin Center for Biodiversity

Features an on-line key and list of tree species with photos.

UI Plants

A database on woody landscape plant identification, culture, and usage for the Midwest, including native and introduced species and their major varieties and cultivars. Search by common or scientific name. Images and information on habitat, leaves, buds, stems, flowers, fruits, fall color, bark, and culture. 

University of Wisconsin-Stevens Point Herbarium

An incredible collection of identification resources including photos, keys, and descriptions of natural communities, fungi, plants, and more.