Dryopteris carthusiana (Spinulose Wood Fern)

Plant Info
Also known as: Spinulose Shield Fern, Toothed Wood Fern
Family:Dryopteridaceae (Wood Fern)
Life cycle:perennial
Habitat:part shade; moist to swampy woods, thickets, stream banks
Fruiting season:summer
Plant height:6 to 30 inches
Wetland Indicator Status:GP: FACW MW: FACW NCNE: FACW
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information


[photo of fiddlehead] Fiddleheads emerge in early spring. They are hairless and have papery tan scales scattered along the stem.

Leaves and stems: Leaf attachment: basal Leaf type: compound

[photo of frond] Leaf is lanceolate to somewhat egg-shaped in outline, to 30 inches long and 8 inches wide, tapering to a sharp point at the tip, twice compound though the lowest pair of branches at the base of the frond are again compound. There are no glandular hairs.

[photo of lowest branch] Leaflets are lobed, sometimes divided almost to mid-nerve, and toothed, the teeth with a bristle-like tip. Veins are forked. On the first branch at the base of the leaf, the leaflet on the lower-side of the branch closest to the stem is longer than the next leaflet and up to twice as long as the leaflet opposite on the upper-side of the branch (see image enlargement). The first pair of leaflets are nearly opposite each other.

[photo of lower stem] The stem is grooved with light-brown scales at base of stem. Leaves are more leaning or prostrate than erect, 1 to several leaves forming a loose asymmetrical clump.

Spores: Fruit type: spores on leaf

[photo of mature spores] The sori (group of spores) are found on the underside of the leaf.  They are circular and arranged mostly in a row on both sides of the mid-vein on a leaflet lobe. Not all leaves have spores and the lowest branches on a fertile frond typically have no spores either.

[photo of indusium] A kidney-shaped, translucent tissue (indusium) partly covers the spores and is attached on inner curve.


Dryopteris species can be identified by the circular shaped sori that is covered by a translucent tissue. Dryopteris carthusiana is most similar to D. expansa and D. intermedia. The best way to distinguish them is by looking at the lowest branch at the base of the leaf. On D. carthusiana, the leaflet closest to the stem on the lower side of the branch is longer than the next leaflet, up to twice as long as the opposing leaflet on the upper side of the branch, with the first pair of leaflets nearly opposite each other. D. expansa also has the first lower leaflet usually longer than the second, but the first leaflet is up to 3 times as long as the upper leaflet and the first pair is further offset than on D. carthusiana. On D. intermedia, the leaflet closest to the stem on the lower side of the branch is noticeably shorter than the next leaflet and there are tiny glandular hairs on the upper stem, visible with a strong hand lens. D. carthusiana lacks glandular hairs.

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More photos

Photos by K. Chayka taken at Falls Creek SNA, Washington County, and at Long Lake Regional Park, Ramsey County. Photos courtesy Peter M. Dziuk taken in Ramsey County.


Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: luciearl - Fairview township, Cass County
on: 2019-10-27 23:24:04

I believe I recently found this fern in my woods. Most of the ferns have died off by now, so took a few pictures of this one still a pretty green nearly the end of Oct.

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