Dichotomous Keys

Dichotomous keys are tools for identification; the user is presented with a series of paired feature descriptions, and at each step chooses the description that best matches their specimen of interest, finally reaching a tentative species identification. This tentative identification should then be checked (e.g., does the geographic range make sense? Do available images look right?) before acceptance as a final answer. Dichotomous keys are by nature artificial (i.e., they don’t reflect evolution, but are a product of taxonomic expertise) and some “work” better than others. Some groups of plants simply lack readily observable diagnostic traits, or the author of a key lacked material from a portion of the geographic range of a taxon. Almost all will require careful inspection of a specimen in order to locate and identify diagnostic morphological characteristics. Depending on the taxa of interest, a 10x hand lens will be required (this applies to most vascular plants) or a stereoscope or compound microscope (for, e.g., bryophytes).

We currently have keys for Ferns and Lycophytes of Wisconsin and Trees of Wisconsin, both of which were built by Gary Fewless; where necessary we are updating the key to reflect taxonomic changes, but have found the keys to work quite well for our flora.