Pteridophytes of Wisconsin:
Ferns and Fern Allies

Introduction to the Keys

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Key to Pteridophytes of Wisconsin

This site provides a key to all Wisconsin pteridophytes with photos and descriptions to help with their identification. If the key is successfully employed to identify an unknown plant, the reader is directed to a page providing photos of the species and some basic information regarding habitat and distribution. The reader can also go directly to a list of Wisconsin ferns and fern allies to get to the photo pages.

It may be tempting to identify unknown plants by comparing them to pictures of known species, but that is a very unreliable method. If you are serious about learning the identity of plants (i.e. if it is important that the answer you arrive at is correct), you must learn to use one of the many keys available for that purpose. Photos can provide insight into the various terms used in the keys, but individual plants are so variable that no picture can adequately represent any particular species.

One of the difficulties for beginners in learning to identify plants rests in a common desire for a single character that will distinguish a particular species. Because of the highly variable nature of plants, it is frequently necessary to consider several characters to make a reliable identification. That is why keys are essential. They group similar species together for careful comparison, and they can describe combinations of characters and a range of possibilities more accurately than is possible in a picture. The task of identifying unknown plants remains a challenge under any circumstances, however, and I have not yet encountered a key for any large group of organisms that can be used successfully without a fair amount of practice by the user.

The key is highly artificial, with the single goal of attempting to employ the most easily recognizeable characters possible, while remaining reliable. It is intended to help students learn the pteridophytes, but it should also serve readers with a background in botany as I have tried never to sacrifice accuracy for ease of use. As in all keys, this one relies heavily on the works of previous authors. In the case of some difficult groups of species the key is directly modeled after the treatments in the Flora of North America, Vol. 2, which has become the most widely used standard for the treatment of pteridophytes in North America and is highly recommended. Those considering the purchase of this publication may examine the contents on the Flora of North America web site or examine the full keys to the families of pteridophytes of North America in volume 2.

The following key includes all native pteridophytes known to occur in Wisconsin. Each page offers two alternatives. Select the choice which best suits the specimen, click on the numeral to the right and you will be presented with another page with another set of choices. This process continues until you reach an answer. Photos used within the key are examples to illustrate the terms and may not be a perfect match for your specimen, especially early in the key where any given step may lie along the path to many subsequent species.

Glossary of terms

Pteridophytes of Wisconsin home page

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Return to list of Pteridophyte species

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