Etymology cristata, Latin, like a comb. The fertile fronds have the pinnae twisted 90°, and thus appear comb-like in profile. The English common name is a mistranslation of the Latin.

Description Rhizome: erect, massive, occasionally branching to form new crowns, covered with old stipe bases.
Frond: 60 cm high by 12 cm wide, fertile deciduous, sterile evergreen, dimorphic, fertile taller, erect, sterile fronds shorter, narrower at base, blade/stipe ratio: 2:1 to 3:1.
Stipe: grooved, base swollen, persistent, scaly at the base, vascular bundles: 5 in a c-shaped pattern.
Blade: 1-pinnate-pinnatifid, narrowly lanceolate or with parallel sides, herbaceous to somewhat leathery, linear to ovate scales below, absent above.
Pinnae: 10 to 15 pair, isodromous, fertile pinnae twisted out of plane of blade, perpendicular to it, lower pinnae distant, triangular, upwards closer, narrower; pinnules oblong, rounded at the apex; costae grooved above, continuous from rachis to costae; margins spiny, serrate, bending slightly down; veins free, forked.
Sori: round, in 1 row between midrib and margin, indusium: reniform, shriveling upon ripening, attached at a sinus, sporangia: dark brown, maturity: midsummer.
Dimensionality: pinnae rotated 90º to a plane parallel to the ground.

Culture Habitat: swamps, swampy woods, or open shrubby wetlands . Distribution: North America (mainly northern), Norway and England across northern and central Europe and northern Asia. Hardy to -35°C, USDA Zone 3.

Synonyms
Polypodium cristatum L.
Aspidium cristatum (L.) Swartz
Nephrodium cristatum (L.) Michaux
Filix cristata Farwell
Lastrea cristata Presl
Polystichum cristatum (L.) Roth