This interactive dichotomous tree key was developed to help identify the most common trees in Iowa. The key is based on vegetative characteristics such as leaves, twigs, fruits, and bark. Check out our definition of special terms page to learn more about the characteristics you'll see in the key. This is not a complete key. It does not include all trees grown in Iowa.
The proper use of the key may be compared to the use of road signs where a choice of two directions must be made at each intersection. One must always choose the best route which matches the characteristics of the tree.
If at the end, the solution does not match the specimen, one can usually identify a point in the process where the choice of direction was in doubt. Many times the steps can be retraced to this point and the sample can be identified.
Acknowledgements: Some of the pictures on these web pages are from USDA's Natural Resources Conservation Service Trees and Shrubs Pocket Guide, The Sibley Guide to Trees, and Forestry Images. Paul Wray, Professor Emeritus, at the Department of Natural Resource and Ecology and Management was the source for most of the original content for these web pages. In 2011, Claudette Sandoval-Green built upon the original design, relocated the tree identification key within ISU Forestry Extension's web site, and updated the content and graphics under the direction of Dr. Jesse Randall. In 2019, the key moved to the new Natural Resources Stewardship site.