Ferns and Fern Allies of Wisconsin

2. Leaves longer than 2 cm, all appearing to originate at ground level (no obvious stem); multiple spores borne in an enclosed space at the abruptly expanded base of individual leaves. Aquatic species, growing submersed on lake bottoms.   Isoetes
2. Leaves shorter than 1 cm., spread out along obvious stems; spores borne in sporangia, in the axils of some upper leaves or in terminal strobili (cone-like structures). Terrestrial or wet soil species, but not commonly submersed. The primary criteria listed below can be difficult to grasp in the abstract, although the two genera are easily distinguished with a little experience.   3

Key to ferns
Glossary of terms
Introduction to ferns
List of all Pteridophytes

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