Checklist » Dryopteridaceae » Dryopteris expansa
Last updated 3/11/2009 by David Giblin.
Dryopteris expansa (C. Presl) Fraser-Jenk. & Jermy[FNA2, HC2]
northern fern, spreading wood fern

Publication: Brit. Fern Gaz. 11: 338. 1977.

Origin: Native

selected vouchers: WTU

Notes: Dryopteris dilatata is European; no distinction between D. expansa and D. carthusiana was made in our floras until recently.

FNA2: "Dryopteris expansa is diploid and is one of the parents of D . campyloptera . Where their ranges overlap in eastern Canada, these two species are very difficult to distinguish except by chromosome number. The growth habit ( D . expansa leaves are more erect) is useful in the field. Three hybrids involving D . expansa are known; all are very rare."

References: (none)

Synonyms & Misapplied Names:
Dryopteris assimilis S. Walker
Dryopteris campyloptera (Kunze) Clarkson, misapplied[FNA2]
Dryopteris dilatata (Hoffm.) A. Gray, misapplied[Abrams, Peck]
Dryopteris dilitata (Hoffm.) A. Gray var. americana (Fisch.) Hultén
Nephrodium expansum C. Presl