Dryopteris marginalis (Marginal Shield Fern)

Plant Info
Also known as: Marginal Wood Fern, Eastern Wood Fern
Genus:Dryopteris
Family:Dryopteridaceae (Wood Fern)
Life cycle:perennial
Origin:native
Status:
  • State Endangered
Habitat:part shade, shade; average moisture, rocky soil; hardwood or mixed forest, bluffs, ravines, wooded slopes, stream banks
Fruiting season:mid-summer
Plant height:12 to 40 inches
Wetland Indicator Status:GP: FACU MW: FACU NCNE: FACU
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

Fiddlehead:

[photo of fiddlehead] Fiddleheads emerge in spring, covered in reddish-brown scales.

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

[photo of leaves] Leaves are evergreen, dark green to bluish-green, twice compound except the uppermost branches, generally lance-shaped in outline, tapering at the tip end, 12 to 40 inches long, 4 to 10 inches wide, with 12 to 16 pairs of branches (pinnae).

[photo of pinnae and pinnule] Branches are lance-oblong in outline, tapering to a point and stalkless. The lowest branches are slightly shorter than those above, and the uppermost branches are not compound but merely lobed. A branch has up to 20 pairs of leaflets (pinnules) in an opposite arrangement, the lowest leaflets usually longer than those adjacent to it. Leaflets are rounded at the tip and toothless to shallowly lobed or toothed with rounded teeth. Veins are forked or freely branched.

[photo of lower stem] Stems are grooved, the lower stem reddish-brown and covered in brown to yellowish scales, the stem base swollen with a dense tuft of scales. The upper stem is green to brownish and lacks scales or hairs. The plant grows in an asymmetrical clump, the fronds spreading in all directions, mostly erect to ascending.

Spores: Fruit type: spores on leaf

[photo of spores] The sori (group of spores) are found on the underside of the leaf. They are circular and arranged along the edge of a leaflet. A kidney-shaped, translucent tissue (indusium) partly covers the spores and is attached on the inner curve. Spores ripen to dark brown or black. Not all leaves have spores and there is no visible difference between fertile and sterile leaves.

Notes:

Marginal Shield Fern is a fern of rocky, hardwood forest, shaded bluffs and rocky slopes. While it resembles other Dryopteris species or even Lady Fern (Athyrium filix-femina), the toothless to shallowly lobed or scalloped pinnules, kidney-shaped indusium and sori along the pinnule edges distinguishes it from the others. It is quite a rare species in Minnesota, where it reaches the western fringe of its US range. According to the DNR, it was first discovered in 1981 when a single population was found in Houston County. Listed as a Threatened species in 1984, it was elevated to Endangered in 2013 after biological surveys found only one additional location, a very small population in Fillmore County. It is, however, available in the nursery trade and has done rather well in our own shade garden.

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More photos

Photos by K. Chayka and Peter M. Dziuk taken in a private garden in Ramsey County. Photos courtesy John Thayer taken in Maine.

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