NamingPolystichum braunii (Spenner) Fée
Polystichum braunii subsp. purshii (Fernald) Calder & Roy L. Taylor
Polystichum braunii var. purshii Fernald
Dryopteris braunii (Spenner) Underw.
Aspidium braunii Spenner
DistributionSt. 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.
StatusWisconsin Threatened Species
Minnesota Threatened Species
HabitatMoist 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.
EvolutionPolystichum 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.
Some text fragments are auto parsed from Wikipedia.https://en.wikipedia.org/wiki/Polystichum