Braun's Holly Fern

Polystichum braunii

Leaves (fronds) are evergreen, up to 1 meter long and 20 cm wide, twice compound, lance-elliptic in outline, widest at about the middle, tapering to a pointed tip and gradually tapering at the base, with branches (pinnae) all along the stem nearly all the way to the ground, the lowest pinnae very short. Pinnae are up to 4 inches long, mostly lance-oblong in outline with 9 to 15 pairs of leaflets (pinnules).

Pinnules are sharply toothed, the teeth with bristled tips and curved up towards the pinnule tip (falcate). The upper surface is dark, glossy green, the lower surface paler. Stems (rachis) are densely covered in tan scales, especially near the base.

Many pinnules, especially near the rachis, typically have a small lobe (auricle) at the base. Veins are forked. Plants grow in an asymmetrical clump of 12 or more fronds, the fronds often arching.
Polystichum braunii On rocks in an ephemeral streambed in a deep ravine. Shaded by Sugar Maple and Black Ash trees. The ferns grow on duff and soil covered boulders in an ephemeral stream that flows between an old-growth Sugar Maple forest and a tall (~90 meters from the base) north-facing basalt bluff.

Same fern as in:
https://www.jungledragon.com/image/79810/polystichum_braunii.html
https://www.jungledragon.com/image/79811/polystichum_braunii.html Braun's Holly Fern,Geotagged,Polystichum braunii,Summer,United States,fern

Naming

Polystichum braunii (Spenner) Fée
Polystichum braunii subsp. purshii (Fernald) Calder & Roy L. Taylor
Polystichum braunii var. purshii Fernald
Dryopteris braunii (Spenner) Underw.
Aspidium braunii Spenner
Polystichum braunii Uncoiling frond of Polystichum braunii found growing on duff and soil covered boulders in an ephemeral stream that flows between an old growth Sugar Maple forest and a tall (~90 meters from the base) north facing basalt bluff. Braun's Holly Fern,Geotagged,Minnesota,Polystichum braunii,Spring,United States,ephemeral stream

Distribution

St. Pierre and Miquelon; B.C., N.B., Nfld., N.S., Ont., Que., Yukon; Alaska, Conn., Idaho, Maine, Mass., Mich., Minn., N.H., N.Y., Vt., Wis.; Eurasia.
Polystichum braunii Polystichum braunii found growing on duff and soil covered boulders in an ephemeral stream that flows between an old growth Sugar Maple forest and a tall (~90 meters from the base) north facing basalt bluff. Braun's Holly Fern,Geotagged,Polystichum braunii,Spring,United States

Status

Wisconsin Threatened Species
Minnesota Threatened Species

Habitat

Moist places in boreal forests; interior moist forests.

In the Western Lake Superior region it is found in rich, hardwood or mixed conifer-hardwood forests near ravine bottoms. It is also often found in areas of cold air drainage, on gentle to moderately steep rocky forested slopes, and at the bases of moist cliffs.

Evolution

Polystichum braunii is an ancient tetraploid that originated in the Late Miocene.

The remarkable genetic uniformity of Polystichum braunii across its circumboreal range revealed in both chloroplast and nuclear sequences suggests that the species, though relatively ancient, has expanded to occupy its current broad range in the recent past. The opening of broad-ranging appropriate habitat in the wake of the last glacial retreat likely provided the opportunity for P. braunii, a highly dispersible species likely capable of selfing, to expand rapidly into its current interrupted circumboreal range.

References:

Some text fragments are auto parsed from Wikipedia.

https://en.wikipedia.org/wiki/Polystichum
https://en.wikipedia.org/wiki/Fern
https://www.minnesotawildflowers.info/fern/brauns-holly-fern
http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=200004566
https://www.dnr.state.mn.us/rsg/profile.html?action=elementDetail&selectedElement=PPDRY0R040
https://dnr.wi.gov/topic/EndangeredResources/Plants.asp?mode=detail&SpecCode=PPDRY0R040
http://ontarioferns.com/main/species.php?id=4015
https://bioone.org/journals/systematic-botany/volume-42/issue-1/036364417X694557/Two-Beringian-Origins-for-the-Allotetraploid-Fern-Polystichum-braunii-Dryopteridaceae/10.1600/036364417X694557.full
Taxonomy
KingdomPlantae
DivisionPolypodiophyta
ClassPolypodiopsida
OrderPolypodiales
FamilyDryopteridaceae
GenusPolystichum
SpeciesPolystichum braunii