Dryopteris carthusiana (Spinulose Wood Fern)
|Also known as:||Spinulose Shield Fern, Toothed Wood Fern|
|Family:||Dryopteridaceae (Wood Fern)|
|Habitat:||part shade; moist to swampy woods, thickets, stream banks|
|Plant height:||6 to 30 inches|
|Wetland Indicator Status:||GP: FACW MW: FACW NCNE: FACW|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Leaves and stems:
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.
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.
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.
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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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.
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