Gymnocarpium dryopteris (L.) Newman
common oak fern
Family: Dryopteridaceae


Fronds of Gymnocarpium dryopteris are usually less than 40 cm long (12-42). The blade ranges from 3-14 cm long and is clearly shorter than the stipe. The blade is broadly triangular, 2- pinnate-pinnatifid and ternate (divided into three roughly equal branches at the base). Sori are round, located on the underside of the blade and there is no indusium. The horizontal stems are elongate so leaves are not densely aggregated. The blades are not glandular, or occasionally there are a few glands on the abaxial (lower) surface. The closely-related species, G. robertianum and G. jessoense differ in the presence of more conspicuously glandular blades, but can be difficult to distinguish.

G. dryopteris ranges from Alaska fully across Canada, south to West Virginia, Ohio and Minnesota. It is also found in the northwestern U.S. and at scattered locations in several other western states and in the Great Plains. It is found nearly throughout Wisconsin, except for a few counties in the southeast, but it is more common in the northern half of the state. Habitats are mostly cool, coniferous or mixed forests, including conifer swamps. Fronds wilt extremely rapidly if picked.

Key to Ferns

Introduction to Ferns

Glossary of terms

List of all Pteridophytes

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