Polystichum is from the Greek polys, many, + stichos, row. The sori are in many rows.
Rhizome: erect, scales.
Frond: evergreen, monomorphic or weakly dimorphic.
Stipe: scaly, vascular bundles: 4 or more, in an arc.
Blade: 1-3 pinnate, lanceolate; at emergence the croziers droop backwards, glossy, linear to lanceolate scales below, no hairs.
Pinnae: usually an upper side lobe, costae grooved above, grooves discontinuous from rachis to costae, segments spinulose, veins free, forked, anadromic.
Sori: round, in 1 (2) rows between midrib and margin, indusium: peltate or rarely absent, central, sporangia: yellow or brownish to black.
similar to Dryopteris, but distinguished by the upward ear on the pinnae, commonly spiny margins, the peltate indusia, and discontinuous grooving between rachis and costa. It also has many characteristics in common with Cyrtomium, but the latter has netted veins; here they are always free, perhaps forked.
Polystichum . The indusium attached at the center (peltate) is characteristic of the genus.
Illustration from Scandinavian Ferns by Benjamin Ĝllgaard and Kirsten Tind, Rhodos, 1993.